Royal Oak was named in 1819, during one of the surveying expeditions led by Territorial Governor Lewis Cass. A large oak tree at this small settlement reminded Cass of the story of the Royal Oak, where King Charles II of England, Scotland and Ireland hid to escape capture by the Roundheads after the Battle of Worcester, so he chose that name for the settlement.

Royal Oak was not incorporated as a village until 1891. It was reincorporated a city in 1921.

Royal Oak developed as a suburb of Detroit in the early 20th century, following Detroit's booming growth as a result of industrialization and its auto industry.

The Royal Oak Farmers Market opened as a truck market, at the corner of 4th and Troy streets, on October 14, 1925, as a cooperative venture between the then-new City of Royal Oak and Oakland County, Michigan. There were still numerous farmers in the county. The present structure, at the corner of 11 Mile Road and Troy Street, is adjacent to the 44th District Court. It was erected in the spring of 1927 and dedicated July 1 of that year.

In the 1920s, Father Charles Coughlin, a Canadian Catholic priest who relocated to Detroit, became the founding pastor of the Shrine of the Little Flower, now a prominent landmark in the city. Through his ministry, he raised funds to build the present limestone church complex and tower. Initially he broadcast religious speeches from this site.

During the 1930s, his broadcasts became more political. He initially supported President Franklin D. Roosevelt, then opposed him and promoted the causes of the fascist leaders of Germany and Italy. The Roosevelt administration closed down his radio operation after the outbreak of World War II, with support from the Catholic hierarchy. Coughlin had developed national political influence and had an increasingly anti-semitic message, at a time when Jewish people were being severely persecuted in Germany.

In 1991, Thomas McIlvane, a postal worker, killed five people in Royal Oak's post office, after being fired from the Postal Service for "insubordination." This incident helped to popularize the term "going postal."

The downtown originally had a typical mixture of small-scale retail and trade to serve the city of Royal Oak. With the development of the highway system in the postwar period, it lost business to suburban malls. Since the late 1990s and early 2000s, however, Royal Oak's downtown has developed as an entertainment and nightlife destination. A number of large condominiums and lofts have been built in the area, increasing the density of the downtown population. In 2022, the Royal Oak City Commission approved the demolition of the historic Main Art Theater, once a symbol of moviegoers in the area.

According to the United States Census Bureau, the city has a total area of 11.79 square miles (30.54 km), of which 11.78 square miles (30.51 km) is land and 0.01 square miles (0.03 km) (0.08%) is water.

Royal Oak developed around a river, the Red Run. Vinsetta Boulevard was built skirting a source branch of the Red Run for its median. In the 1930s, Vinsetta's entire median, along with the river and all but the tops of the bridges for the crossing streets were filled in as part of a WPA project during the Great Depression. During 1967–8, the rest of the river in Oakland County was buried within a six-foot drain pipe.

Extensive tree-planting has taken place since the 1930s, leading to the town being nicknamed "The City of Trees", although recent increased developments have caused controversy about the maintenance of the city's urban forest.

This section needs expansion with: income data for the 2010 and 2020 censuses. You can help by adding to it. (February 2025)

As of the census of 2020, there were 58,211 people and 28,971 households in the city. The racial makeup of the city was 86.1% White, 5.6% African American, 0.1% Native American, 3.7% Asian American, and 1.9% from two or more races. Hispanic or Latino of any race were 4.5% of the population.

5.4% of residents were under the age of 5, 15.2% of residents were under the age of 18, and 14.1% were 65 years of age or older. The gender makeup of the city was 51.0% male and 49.0% female.

As of the census of 2010, there were 57,236 people, 28,063 households, and 13,394 families living in the city. The population density was 4,854.6 inhabitants per square mile (1,874.4/km). There were 30,207 housing units at an average density of 2,562.1 per square mile (989.2/km). The racial makeup of the city was 90.7% White, 4.3% African American, 0.3% Native American, 2.4% Asian American, 0.4% from other races, and 1.9% from two or more races. Hispanic or Latino of any race were 2.3% of the population.

There were 28,063 households, of which 20.0% had children under the age of 18 living with them, 36.7% were married couples living together, 8.1% had a female householder with no husband present, 3.0% had a male householder with no wife present, and 52.3% were non-families. 41.4% of all households were made up of individuals, and 10.7% had someone living alone who was 65 years of age or older. The average household size was 2.03 and the average family size was 2.82.

The median age in the city was 37.8 years. 16.7% of residents were under the age of 18; 7.6% were between the ages of 18 and 24; 35.9% were from 25 to 44; 26.8% were from 45 to 64; and 13.1% were 65 years of age or older. The gender makeup of the city was 49.0% male and 51.0% female.

As of the census of 2000, there were 60,062 people, 28,880 households, and 14,440 families living in the city. The population density was 5,083.0 inhabitants per square mile (1,962.6/km). There were 29,942 housing units at an average density of 2,534.0 per square mile (978.4/km). The racial makeup of the city was 94.80% White, 1.54% African American, 0.26% Native American, 1.56% Asian, 0.05% Pacific Islander, 0.38% from other races, and 1.40% from two or more races. Hispanic or Latino of any race were 1.30% of the population.

There were 28,880 households, out of which 20.4% had children under the age of 18 living with them, 39.9% were married couples living together, 7.5% had a female householder with no husband present, and 50.0% were non-families. 40.8% of all households were made up of individuals, and 11.6% had someone living alone who was 65 years of age or older. The average household size was 2.06 and the average family size was 2.86.

In the city, the population was spread out, with 17.8% under the age of 18, 7.5% from 18 to 24, 38.8% from 25 to 44, 21.0% from 45 to 64, and 14.9% who were 65 years of age or older. The median age was 37 years. For every 100 females, there were 95.3 males. For every 100 females age 18 and over, there were 92.6 males.

The median income for a household in the city was $52,252, and the median income for a family was $68,109. Males had a median income of $50,562 versus $36,392 for females. The per capita income for the city was $30,990. About 2.0% of families and 4.3% of the population were below the poverty line, including 3.4% of those under age 18 and 5.5% of those age 65 or over.

Royal Oak has a below-average crime rate, similar to that of nearby middle-class communities, such as Berkley and Madison Heights. Larceny-theft was the most common crime, making up 66.7% of all crimes in the city. Five known murders have been committed since 2000, one in 2004, one in 2005, one in 2010, and two in 2011.

Royal Oak has a Council–manager government. It is governed by a city commission consisting of a mayor and six commission members. The city commission appoints a city manager, who manages the day-to-day operations of the city.

The city is served by Royal Oak Neighborhood Schools. Private K-12 education is also offered by Shrine of the Little Flower Catholic Church while nearby St. Mary's offers K-8 instruction. A branch of Oakland Community College is located in the city and a new location of Baker College is nearing the end of construction.

A portion of land in the city is zoned to Berkley Public Schools.

In recent years Royal Oak has begun to consolidate its public schools in response to a decline in enrollment levels compared to the baby boom era. In 2006, the city's two public high schools, George A. Dondero High School and Clarence M. Kimball High School, were combined into a new Royal Oak High School. Beginning in 2007, the city's two middle schools were combined into one school, Royal Oak Middle School, in the former Dondero building. The number of elementary schools was reduced to six. Some parents protested the planned closure and demolition of Longfellow and Whittier elementary schools. They were seeking to have them considered for historic district recognition by way of signed petition. Despite their efforts, both schools and a number of other former elementary schools were demolished in the fall of 2007.

The Royal Oak school system gained brief notoriety for an incident following the Trump election. Some middle schoolers chanted "build that wall". A student video of the incident was widely shared on Facebook, attracting more than 4 million views within 24 hours. A week later a noose was found in the 8th grade boys bathroom at the middle school. The student who had placed the noose in the bathroom was removed from the school shortly afterward.

St. Dennis School of the Roman Catholic Archdiocese of Detroit was formerly in Royal Oak. It closed in 2011.