In the late 19th century Brentwood grew as a community, and still is known all through the Bay Area for its rural products, basically its fruits, corn and peaches. Because of urban sprawl since 1990, a hefty portion of the old homesteads and orchards have been supplanted by suburban developments
Brentwood was initially laid out on land donated from the property of John Marsh, an East Contra Costa County settler who owned Rancho Los Meganos, the grant of land that Brentwood is built upon Jose Noriega. Bog was one of the wealthiest men in California in 1837 and was instrumental in its obtaining independence from Mexico. His letters lauding the potential of California agriculture were published in daily newspapers all through the East. They brought about the primary wagon trains to California. Marsh encouraged this, and permitted new arrivals to remain on his ranch until they became settled. Rancho Los Meganos became the end of the California Trail. Brentwood was named after Marsh's genealogical hometown in the County of Essex, England.
Brentwood's first post office was set up in 1878. The city was incorporated in 1948.
In 1910, Balfour, Guthrie and Co., a British venture organization, obtained the John Marsh Ranch. The organization vigorously invested in other California agricultural properties too. In 1910, it constructed the Brentwood Hotel at Brentwood Boulevard and Oak Street, opposite the railroad station. It replaced an earlier hotel on the site that had burned in 1903. The lodging was demolished in 1967, and replaced by a gas station.
The Brentwood water tower maybe symbolizes the city's move from a rural farm community to a cutting edge bedroom community. This point of interest on Walnut Boulevard, across the road from the Brentwood Park and Ride parking lot, is the tallest city structure. It is no longer utilized for its original purpose, however now serves as a cell tower. City water is stored in expansive tanks on slopes outside the city.
Three of the city's borders adjoin the Contra Costa County Agricultural Core, made up of of 11,000 acres of land of preserved and still effectively gainful farm land.
Amid the 1990s, many retail businesses were built along the border between Brentwood and Antioch on Lone Tree Way, and on both sides of SR 4 B, around 3.5 miles from Brentwood's downtown. An outdoor lifestyle retail center, "The Streets of Brentwood", was opened in Brentwood in 2008.
In November, 2009, The city announced a new civic center. The Mission-style City Hall complex, the primary building, was the Brentwood Hotel in 1910. The $60 million venture, finished in May 2012, incorporates the 58,000-square-foot City Hall and best in class City Council Chambers, a 32,000-square-foot community center, a parking structure with 280 spaces and redevelopment of the 2½-acre of land City Park. The community center incorporates arts and crafts rooms along with dance classe studios and community exercise programs. The center got a Leadership in Energy and Environmental Design Silver accreditation for amemities, for example, green rooftops, bioswales, permeable paving and planters. In October, 2011, city offices moved into the new facility, and the previous city hall was leveled in November 2011.