Before settlement by members of the LDS Church, the Shoshone, Weber Ute, and Paiute had dwelt in the Salt Lake Valley for thousands of years. At the time of Salt Lake City's founding, the valley was within the territory of the Northwestern Shoshone. One local Shoshone tribe, the Western Goshute tribe, had names for the Jordan River, City Creek, and Red Butte Canyon (Pi'o-gwût, So'ho-gwût, and Mo'ni-wai-ni). The Goshutes (or, Gosiutes) also lived in the vicinity of Salt Lake and the valleys to the west. The land was treated by the United States as public domain; no aboriginal title by the Northwestern Shoshone was ever ceded or relinquished by treaty with the United States. The first explorer of European descent in the Salt Lake area was likely Jim Bridger in 1825, although others had been in Utah earlier, some as far north as the nearby Utah Valley (the 1776 Dominguez-Escalante expedition were undoubtedly aware of Salt Lake Valley's existence). U.S. Army officer John C. Frémont surveyed the Great Salt Lake and the Salt Lake Valley in 1843 and 1845. The Donner Party, a group of ill-fated pioneers, had traveled through the Great Salt Lake Valley in August 1846.

The settling of Salt Lake City dates to the arrival of the Latter-day Saints in July 1847. They had traveled beyond the boundaries of the United States into Mexican Territory seeking a secluded area to safely practice their religion away from the violence and the persecution they experienced in the United States. Upon arrival at the Salt Lake Valley, president of the church Brigham Young is recorded as stating, "This is the right place, drive on." Brigham Young is said to have seen the area in a vision before the wagon train's arrival. They found the broad valley empty of any human settlement.

There was a Native American population in the valley, but an outbreak of measles during the winter of 1847 killed many. The Shoshone saved the pioneers when they taught them to eat the bulb of the native sego lily, which has long been part of the ordinary diet of the Shoshone, sego being derived from the Shoshone word seego. The sego lily was commemorated by the Sego Lily Dam, a flood-prevention infrastructure project in the shape of a giant sego lily, built in Sugar House Park in 2017.

Four days after arriving in the Salt Lake Valley, Brigham Young designated the building site for the Salt Lake Temple. The Salt Lake Temple, constructed on the block later called Temple Square, took 40 years to complete. Construction started in 1853, and the temple was dedicated on April 6, 1893. The temple has become an icon for the city and serves as its centerpiece. The southeast corner of Temple Square is the point of reference for the Salt Lake meridian, and for all addresses in the Salt Lake Valley.

The pioneers organized a state called State of Deseret, and petitioned for its recognition in 1849. The United States Congress rebuffed the settlers in 1850 and established the Utah Territory, vastly reducing its size, and designated Fillmore as its capital city. Great Salt Lake City replaced Fillmore as the territorial capital in 1856, and the name later was shortened to Salt Lake City. The city's population continued to swell with an influx of converts to the LDS Church and Gold Rush gold seekers, making it one of the most populous cities in the American Old West.

The first group of settlers brought African slaves with them, making Utah the only place in the western United States to have African slavery. Three slaves, Green Flake, Hark Lay, and Oscar Crosby, came west with the first group of settlers in 1847. The settlers also began to purchase Indian slaves in the well-established Indian slave trade, as well as enslaving Indian prisoners of war. In 1850, 26 slaves were counted in Salt Lake County. In 1852, the territorial legislature passed the Act in Relation to Service and the Act for the relief of Indian Slaves and Prisoners formally legalizing slavery in the territory. Slavery was abolished in the territory during the Civil War.

Explorer, ethnologist, and author Richard Francis Burton traveled by coach in the summer of 1860 to document life in Great Salt Lake City. He was granted unprecedented access during his three-week visit, including audiences with Brigham Young and other contemporaries of Joseph Smith. The records of his visit include sketches of early city buildings, a description of local geography and agriculture, commentary on its politics and social order, essays, speeches, and sermons from Young, Isaac Morley, George Washington Bradley and other leaders, and snippets of everyday life such as newspaper clippings and the menu from a high-society ball.

Disputes with the federal government ensued over the church's practice of polygamy. A climax occurred in 1857 when President James Buchanan declared the area in rebellion after Brigham Young refused to step down as governor, beginning the Utah War. A division of the United States Army, commanded by Albert Sidney Johnston, later a general in the army of the Confederate States of America, marched through the city and found it had been evacuated. They continued their march through the deserted city to vacant land at the southwest corner of the valley. There they set up Camp Floyd (40 miles (64 km) south of the city). Another military installation, Fort Douglas, was established in 1862 to maintain Union allegiance during the American Civil War. Many area leaders were incarcerated at the territorial prison in Sugar House in the 1880s for violation of anti-polygamy laws. The church began its eventual abandonment of polygamy in 1890, releasing "The Manifesto", which officially suggested members obey the law of the land (which was equivalent to forbidding new polygamous marriages inside the US and its territories, but not in church member settlements in Canada and Mexico). This paved the way for statehood in 1896, when Salt Lake City became the state capital.

The First Transcontinental Railroad was completed in 1869 at Promontory Summit on the north side of the Great Salt Lake. A railroad was connected to the city from the Transcontinental Railroad in 1870, making travel less burdensome. Mass migration of different groups followed. Ethnic Chinese (who had laid most of the Central Pacific railway) established a flourishing Chinatown in Salt Lake City nicknamed "Plum Alley", which housed around 1,800 Chinese during the early 20th century. The Chinese businesses and residences were demolished in 1952 although a historical marker has been erected near the parking ramp which has replaced Plum Alley. Immigrants also found economic opportunities in the booming mining industries. Remnants of a once-thriving Japantown – namely a Buddhist temple and Japanese Christian chapel – remain in downtown Salt Lake City. European ethnic groups and East Coast missionary groups constructed St. Mark's Episcopal Cathedral in 1874, B'nai Israel Temple in 1890, the Roman Catholic Cathedral of the Madeleine in 1909 and the Greek Orthodox Holy Trinity Cathedral in 1923. This time period also saw the creation of Salt Lake City's now defunct red-light district that employed 300 courtesans at its height before being closed in 1911.

During the late 19th and early 20th centuries, an extensive streetcar system was constructed throughout the city, with the first streetcar running in 1872 and electrification of the system in 1889. As in the rest of the country, the automobile usurped the streetcar, and the last trolley was approved for conversion in 1941, yet ran until 1945, due to World War II. Trolley buses ran until 1946. Light rail transit returned to the city when UTA's TRAX opened in 1999. The S Line (formerly known as Sugar House Streetcar) opened for service in December 2013 on an old D&RGW right-of-way.

The city's population began to stagnate during the 20th century as population growth shifted to suburban areas north and south of the city. Few of these areas were annexed to the city, while nearby towns incorporated and expanded. As a result, the population of the surrounding metropolitan area greatly outnumbers Salt Lake City. A major concern of recent government officials has been combating inner-city commercial decay. The city lost population from the 1960s through the 1980s, but experienced some recovery in the 1990s. Presently, the city has gained an estimated 5 percent of its population since the year 2000.

The city has experienced significant demographic shifts in recent years.Hispanics now account for approximately 22% of residents and the city has a significant LGBT community. There is also a large Pacific Islander population (mainly Samoans and Tongans; they compose roughly 2% of the population of the Salt Lake Valley area.

Salt Lake City was selected in 1995 to host the 2002 Winter Olympics. The games were plagued with controversy. A bid scandal surfaced in 1998 alleging bribes had been offered to secure the bid. During the games, other scandals erupted over contested judging scores and illegal drug use. Despite the controversies, the games were heralded as a financial success, being one of the few in recent history to turn a profit. In preparation major construction projects were initiated. Local freeways were expanded and repaired, and a light rail system was constructed. Olympic venues are now used for local, national, and international sporting events and Olympic athlete training. Tourism has increased since the Olympic games,^{[failed verification]} but business did not pick up immediately following. Salt Lake City expressed interest in bidding for the 2022 Winter Olympics. However, Beijing was selected to host the 2022 Winter Olympics.

Salt Lake City hosted the 16th Winter Deaflympic games in 2007, taking place in the venues in Salt Lake City and Park City, and Rotary International chose the city as the host site of their 2007 convention, which was the single largest gathering in Salt Lake City since the 2002 Winter Olympics. The U.S. Volleyball Association convention in 2005 drew 39,500 attendees.

In 2020, the city experienced a 5.7 magnitude earthquake, protests against the killing of Bernardo Palacios-Carbajal, and a damaging windstorm with hurricane-force winds, amidst the wider national George Floyd protests, the global COVID-19 pandemic, and protests against pandemic measures.

US Census Bureau estimates for 2019 listed 200,567 people in Salt Lake City. The racial makeup of the county was 65.8% non-Hispanic White, 2.6% Black, 1.5% Native American, 5.4% Asian, 1.6% Pacific Islander, and 3.3% from two or more races. 21.8% of the population were Hispanic or Latino of any race.

At the 2010 census, Salt Lake City's population was 75.1% White, 2.6% African American, 1.2% American Indian and Alaska Native, 4.4% Asian, 2.0% Native Hawaiian and other Pacific Islander, 10.7% from other races and 3.7% of mixed descent. 22.3% of the total population were Hispanic or Latino of any race. The city's population has historically been predominantly white. Between 1860 and 1950 whites represented about 99% of the city's population but this somewhat changed in the decades that followed.

As of 2010, 37.0% of the population had a bachelor's degree or higher. 18.5% of the population was foreign born and another 1.1% was born in Puerto Rico, U.S. insular territories, or born abroad to American parent(s). 27.0% spoke a language other than English at home.

There were 186,440 people (up from 181,743 in 2000), 75,177 households, and 57,543 families in the city. This amounts to 6.75% of Utah's population, 18.11% of Salt Lake County's population, and 16.58% of the new Salt Lake metropolitan population. The area within the city limits covers 14.2% of Salt Lake County. Salt Lake City was more densely populated than the surrounding metro area with a population density of 1,688.77/sqmi (1,049.36/km²). There were 80,724 housing units at an average density of 731.2/sqmi (454.35/km²).

The Salt Lake City-Ogden metropolitan area, which included Salt Lake, Davis, and Weber counties, had a population of 1,333,914 in 2000, a 24.4% increase over the 1990 figure of 1,072,227. Since the 2000 Census, the Census Bureau has added Summit and Tooele counties to the Salt Lake City metropolitan area, but removed Davis and Weber counties and designated them as the separate Ogden-Clearfield metropolitan area. The Salt Lake City-Ogden-Clearfield combined statistical area, together with the Provo-Orem metropolitan area, which lies to the south, had a combined population of 2,094,035 as of July 1, 2008.

There were 75,177 households, out of which 27.0% had children under the age of 18 living with them, 41.1% were married couples living together, 10.2% had a female householder with no husband present, and 44.3% were other types of households. Of the 75,177 households, 3,904 were reported to be unmarried partner households: 3,047 heterosexual, 458 same-sex male, and 399 same-sex female. 33.2% of all households were made up of individuals, and 9.7% had someone living alone who was 65 years of age or older. The average household size was 2.48, and the average family size was 3.24.

The city's age distribution (as of 2000):

The median age was 30 years. For every 100 females, there were 102.6 males. For every 100 females age 18 and over, there were 101.2 males. The median income for a household in the city was $36,944, and the median income for a family was $45,140. Males had a median income of $31,511 versus $26,403 for females. The per capita income for the city was $20,752. 15.3% of the population and 10.4% of families were below the poverty line. Out of the total population, 18.7% of those under the age of 18 and 8.5% of those 65 and older were living below the poverty line.

Large family sizes and low housing vacancy rates, which have inflated housing costs along the Wasatch Front, have led to one out of every six residents living below the poverty line.

According to the Census Bureau's American Community Survey of 2017, the highest disparity in income in Utah is in Salt Lake City. Salt Lake City's GINI Index score was 0.4929, compared with the state's overall score of 0.423. The west-side areas of Salt Lake have the lowest-incomes while areas like the upper Avenues, have much higher incomes. Other Utah cities with relatively high scores include Provo, 0.4734; and Ogden, 0.4632.

Less than 50% of Salt Lake City's residents are members of the LDS Church. This is a much lower proportion than in Utah's more rural municipalities; altogether, LDS members make up about 62% of Utah's population.

The Rose Park and Glendale sections are predominantly Spanish-speaking with Hispanic and Latino Americans accounting for 60% of public school-children. The Centro Civico Mexicano acts as a community gathering point for the Wasatch Front's estimated 300,000 Latinos, Mexican President Vicente Fox began his 2006 US tour in Salt Lake City.

Salt Lake City is home to a Bosnian American community of more than 8,000, most of whom arrived during the Bosnian War in the 1990s. The large Pacific Islander population, mainly Samoan and Tongan, is also centered in the Rose Park, Glendale, and Poplar Grove sectors. Most of Salt Lake City's ethnic Pacific Islanders are members of the LDS Church, though various Samoan and Tongan-speaking congregations are situated throughout the Salt Lake area including Samoan Congregational, Tongan Wesleyan Methodist, and Roman Catholic. Just outside Salt Lake City limits, newer immigrant communities include Nepalis, and refugees of Karen origin from Myanmar (former Burma). Salt Lake City also has the third largest Sri Lankan community in the United States.

Salt Lake City has been considered one of the top 51 "gay-friendly places to live" in the U.S. The city is home to a large, business savvy, organized, and politically supported gay community. Leaders of the Episcopal Church's Diocese of Utah, as well as leaders of Utah's largest Jewish congregation, the Salt Lake Kol Ami, along with three elected representatives of the city identify themselves as gay. These developments have attracted controversy from socially conservative officials representing other regions of the state. A 2006 study by UCLA estimated approximately 7.6% of the city's population, or almost 14,000 people, were openly gay or bisexual, compared to just 3.7%, or just over 60,000 people, for the metropolitan area as a whole.

In 2007, Salt Lake City was ranked by Forbes as the most vain city in America, based on the number of plastic surgeons per 100,000 and their spending habits on cosmetics, which exceed cities of similar size. However, this likely reflects a concentration of plastic surgeons within the city limits but whose client base includes the entire metropolitan area.^{[citation needed]}Forbes also found the city to be the 8th most stressful. In contrast to the 2007 ranking by Forbes, a 2010 study conducted by Portfolio.com and bizjournals concluded Salt Lake City was the least stressful city in the United States. In 2014, CNN deemed Salt Lake City to be the least stressed-out city in the United States, citing the low cost of living and abundance of jobs.

A 2008 study by the magazines Men's Health and Women's Health found Salt Lake City to be the healthiest city for women by looking at 38 different factors, including cancer rates, air quality, and the number of gym memberships.