Construction The Prospect Avenue station was constructed as part of the Fourth Avenue Line, the plan for which was initially adopted on June 1, 1905. The Rapid Transit Commission was succeeded on July 1, 1907, by the
New York State Public Service Commission (PSC), which approved the plan for the line in late 1907. The contract for the section of the line that included the Prospect Avenue station, Route 11A3, which extended from 10th Street to 27th Street, was awarded on May 22, 1908, to the Tidewater Building Company and Thomas B. Bryson for $2,043,162.31 (). The
New York City Board of Estimate approved the contract on October 29, 1909. Construction on the segment started on December 20, 1909, and was completed in May 1912. The station's opening was marked with a competition between two trains heading from
Chambers Street station in Manhattan to the Coney Island station, one heading via the
West End Line and the other via the Sea Beach Line; the latter got to Coney Island first. Though the Transit Commission ordered the BMT to lengthen these platforms in September 1923, no further progress was made until February 16, 1925, when the
New York City Board of Transportation (NYCBOT) commissioned its engineers to examine platform-lengthening plans for this and eleven other stations along the Fourth Avenue Line. It estimated the project would cost $633,000 (). The NYCBOT received bids for the project on February 25, 1926. The contract was awarded to the Corson Construction Company for $345,021 (). The extensions opened on August 1, 1927.
1950s and 1960s The city government took over the BMT's operations on June 1, 1940. In July 1959, the
New York City Transit Authority (NYCTA) announced that it would install
fluorescent lighting at the Prospect Avenue station and five other stations along the Fourth Avenue Line for between $175,000 and $200,000. Bids on the project were to be advertised on August 7, 1959 and completed by fall 1960. In the 1960s, the NYCTA started a project to lengthen station platforms on its lines in Southern Brooklyn to to accommodate 10-car trains. On July 14, 1967, the NYCTA awarded a contract to conduct test borings at eleven stations on the Fourth Avenue Line, including Prospect Avenue, to the W. M. Walsh Corporation for $6,585 () in preparation of the construction of platform extensions. The NYCTA issued an invitation for bids on the project to extend the platforms at stations along the Fourth Avenue Line between
Pacific Street and
36th Street, including those at Prospect Avenue, on March 28, 1969. Funding for the renovation projects came out of the NYCTA's 1969–1970 Capital Budget, costing $8,177,890 () in total. As part of the renovation project, the station's platforms were extended,
2017 Under the
Metropolitan Transportation Authority's 2015–2019 Capital Program, the station, along with thirty other New York City Subway stations, were scheduled to undergo a complete overhaul as part of the
Enhanced Station Initiative. Upgrades were to include cellular service, Wi-Fi, USB charging stations, interactive service advisories and maps. From January to May 2016,
Grimshaw Architects worked on a design for the station's renovation, with
Arup Group acting as a consultant. to Citnalta-Forte Joint Venture for $72 million, the first
design–build contract in the subway system's history. The station closed on June 5, 2017 for these renovations, and reopened on November 2, 2017, a month ahead of schedule. ==Station layout==