As early as 1903, William Barclay Parsons, chief engineer of the Rapid Transit Commission, had proposed constructing a four-track extension of the IRT line under Flatbush Avenue, running southeast from Atlantic Avenue to Grand Army Plaza.

[4] As part of the Dual Contracts, two lines under Flatbush Avenue, one each operated by the BRT and IRT, were approved.

[9] Service on the IRT Eastern Parkway Line had been extended from Atlantic Avenue to Utica Avenue in August 1920,[10] but the Bergen Street, Grand Army Plaza, and Eastern Parkway–Brooklyn Museum stations were not ready to open with the rest of the line.

[13] During the 1964–1965 fiscal year, the platforms at Bergen Street, along with those at four other stations on the Eastern Parkway Line, were lengthened to 525 feet (160 m) to accommodate a ten-car train of 51 foot (16 m) IRT cars.

The name tablets read "BERGEN ST." in gold serif font on a blue background and multi-layered green border.

At either ends of both platforms, where they were extended in 1964–1965,[14] there are cinderblock tiles with signs reading "BERGEN ST" in sans serif font on a maroon background.

[citation needed] Each platform has one same-level fare control area at the center and there are no crossovers or crossunders.