The $525 million Motor Mart Garage redevelopment will add 231 condos in a new 310-foot tower and provide financial support for a planned 85-unit affordable housing complex in Chinatown.

The Boston Planning & Development Agency’s board of directors approved plans by garage owner CIM Group and Boston Global Investors for the Back Bay project Thursday. The existing 8-story, 421,000-square-foot garage at 201 Stuart St. contains 1,037 spaces and is located on a 1.2-acre parcel.

The redevelopment, designed by Boston-based CBT Architects, calls for 231 condos in a 20-story, 264,000-square-foot tower rising from the garage’s top floor. A portion of the existing garage will be converted into condos, reducing capacity to 672 spaces.

Developers also plan changes to the garage’s 46,000-square-foot retail component, retaining retail spaces at the building’s four corners while converting part of the basement level for a potential 15,000-square-foot small grocery store.

To comply with Boston’s inclusionary development policy, developers designated the Chinese Consolidated Benevolent Assoc. and Beacon Communities as recipient of their off-site affordable housing contribution. The two groups are in BPDA permitting for an 85-unit affordable apartment complex at 288 Harrison Ave., with units reserved for households earning 60 percent or less of the area median income.