The earliest recorded purchases of land in what was known as Troy Township occurred in 1819. A couple of years later, a settlement known as Troy Corners was established due to Johnson Niles buying 160 acres in the region. The area is currently the north-central area of Troy. In 1827 Troy Township was established. In 1955, Troy was officially incorporated primarily as a strategy for preventing border cities from taking more land. This also helped to establish more robust city services for Troy residents, whose numbers increased rapidly during this time due to Detroiters fleeing the city for the surrounding suburbs.

It was named after Troy, New York and the ancient city of Troy as many of the early settlers, as in much of Michigan, originated from New York.

According to the United States Census Bureau, the city has a total area of 33.64 square miles (87.13 km), of which 33.47 square miles (86.69 km) is land and 0.17 square miles (0.44 km) (0.51%) is water.

According to a 2018 estimate, the median income for a household in the city was $96,864, and the median income for a family was $113,640. Males had a median income of $72,005 versus $52,365 for females. The per capita income for the city was $46,664. About 5.1% of families and 7.2% of the population were below the poverty line, including 6.7% of those under age 18 and 6.1% of those age 65 or over.

As of the census of 2020, there were 87,294 people, 33,822 households, and 24,300 families living in the city. The population density was 2,609.9 inhabitants per square mile (1,007.7/km). There were 34,953 housing units at an average density of 1,044.9 inhabitants per square mile (403.4/km). The racial makeup of the city was 62.2% White, 4.0% African American, 0% Native American, 27.3% Asian, 1.2% from other races, and 5.1% from two or more races. Hispanic or Latino residents of any race were 2.2% of the population.

There were 33,822 households, of which 35.4% had children under the age of 18 living with them, 60.1% were married couples living together, 8.3% had a female householder with no husband present, 3.4% had a male householder with no wife present, and 28.2% were non-families. 23.2% of all households were made up of individuals, and 10.1% had someone living alone who was 65 years of age or older. The average household size was 2.56 and the average family size was 3.05.

The median age in the city was 43.9 years. 20.7% of residents were under the age of 18; 8.8% were between the ages of 18 and 24; 32% were from 25 to 44; 28.6% were from 45 to 64; and 19.7% were 65 years of age or older. The gender makeup of the city was 50.5% male and 49.5% female.

As of the census of 2010, there were 80,980 people, 30,703 households, and 22,443 families living in the city. The population density was 2,419.5 inhabitants per square mile (934.2/km). There were 32,907 housing units at an average density of 983.2 per square mile (379.6/km). The racial makeup of the city was 74.1% White, 4.0% African American, 0.2% Native American, 19.1% Asian, 0.6% from other races, and 2.0% from two or more races. Hispanic or Latino residents of any race were 2.1% of the population.

There were 30,703 households, of which 34.7% had children under the age of 18 living with them, 62.8% were married couples living together, 7.3% had a female householder with no husband present, 3.0% had a male householder with no wife present, and 26.9% were non-families. 23.4% of all households were made up of individuals, and 9.6% had someone living alone who was 65 years of age or older. The average household size was 2.63 and the average family size was 3.14.

The median age in the city was 41.8 years. 23.8% of residents were under the age of 18; 6.7% were between the ages of 18 and 24; 24% were from 25 to 44; 31.6% were from 45 to 64; and 13.8% were 65 years of age or older. The gender makeup of the city was 49.3% male and 50.7% female.

From the census of 2000, there were 80,959 people, 30,018 households, and 21,883 families living in the city. The population density was 2,413.9 inhabitants per square mile (932.0/km). There were 30,872 housing units at an average density of 920.5 per square mile (355.4/km). The racial makeup of the city was 82.30% White, 2.09% African American, 0.15% Native American, 13.25% Asian, 0.02% Pacific Islander, 0.36% from other races, and 1.82% from two or more races. 1.46% of the population was Hispanic or Latino of any race.

There were 30,018 households, out of which 36.9% had children under the age of 18 living with them, 64.5% were married couples living together, 6.0% had a female householder with no husband present, and 27.1% were non-families. 22.8% of all households were made up of individuals, and 7.8% had someone living alone who was 65 years of age or older. The average household size was 2.69 and the average family size was 3.23.

In the city 26.2% of the population was under the age of 18, 6.7% from 18 to 24, 29.8% from 25 to 44, 27.1% from 45 to 64, and 10.2% who were 65 years of age or older. The median age was 38 years. For every 100 females, there were 98.1 males. For every 100 females age 18 and over, there were 94.8 males.

From 1990 to 2000, of all of the municipalities in Oakland, Wayne, and Macomb counties, Troy had the highest numeric growth in the Asian population. It had 4,932 Asians according to the 1990 U.S. Census and 10,730 according to the 2000 U.S. Census, an increase of 5,798. The increase gave Troy the largest Asian-American population in the tri-county area, surpassing that of Detroit.

Troy uses the council–manager form of government, and thus is governed by a city council consisting of a mayor and six council members. The current mayor is Ethan Baker, who was elected to a four-year term on November 5, 2019. The city council appoints a City Manager, who manages the day-to-day operations of the city.

Troy is the location of Walsh College, a business school, as well as branches of the University of Phoenix, Northwood University, Central Michigan University, Spring Arbor University, International Academy of Design and Technology, and Michigan State University.

There are seven school districts serving Troy; however, Troy School District serves the majority of the city limits. The district has multiple elementary schools, four middle schools, and two zoned high schools: Troy High School and Athens High School.

Three school districts have sizable portions of territory in Troy and operate at least one elementary school within the city: Avondale School District, in the north and northwestmost portion of the city; Birmingham City School District, in the southwestmost portion; and Warren Consolidated Schools, in the southeast, which operates Susick Elementary within the city. In addition, two other school districts are located in part in Troy but have no schools within the city limits: Bloomfield Hills School District, with a portion of the northwest part of the city, and Royal Oak School District, which has a very small portion of the southern part of the city. Finally, a small area of commercial property also in the south lies within the borders of Lamphere Public Schools

The Troy School District also hosts the eastern campus of the International Academy. Private schools include Bethany Christian School, Brookfield Academy, Oakland Children's Academy, St. Mark Christian Academy and Troy Adventist Academy.