The 23rd Street station was constructed for the Interborough Rapid Transit Company (IRT) as part of the city's first subway line, which was approved in 1900.

Construction of the line segment that includes the 23rd Street station started on September 12 of the same year.

[6]: 21  However, development of what would become the city's first subway line did not start until 1894, when the New York State Legislature passed the Rapid Transit Act.

It called for a subway line from New York City Hall in lower Manhattan to the Upper West Side, where two branches would lead north into the Bronx.

[7]: 3  A plan was formally adopted in 1897,[6]: 148  and all legal conflicts concerning the route alignment were resolved near the end of 1899.

[6]: 161  The Rapid Transit Construction Company, organized by John B. McDonald and funded by August Belmont Jr., signed the initial Contract 1 with the Rapid Transit Commission in February 1900,[8] in which it would construct the subway and maintain a 50-year operating lease from the opening of the line.

[7]: 4  Belmont incorporated the Interborough Rapid Transit Company (IRT) in April 1902 to operate the subway.

East Side local trains ran from City Hall to Lenox Avenue (145th Street).

[11] To address overcrowding, in 1909, the New York Public Service Commission proposed lengthening the platforms at stations along the original IRT subway.

[12]: 168  As part of a modification to the IRT's construction contracts made on January 18, 1910, the company was to lengthen station platforms to accommodate ten-car express and six-car local trains.

[15][16] The commission postponed the platform-lengthening project in September 1923, at which point the cost had risen to $5.6 million.

Additional columns between the tracks, spaced every 5 feet (1.5 m), support the jack-arched concrete station roofs.

An ornate fare control grille on the southbound side is a piece of artwork entitled Long Division by artist Valerie Jaudon, which was installed during the renovation.

[38] The station features a back-lit "23 Street/Park Avenue South" sign at the platform level fare control.

The northwestern corner stair, for the southbound platform, is within the One Madison Avenue office tower and contains a passageway into the basement of the same building.

[41]: 31  There were store windows on the southern side of the passageway, overlooking the Mercantile Building's basement storefront.

Another sealed passageway leads from the northbound platform to the lobby of 303 Park Avenue South, at the northeast corner with 23rd Street.

In the 1998 film Godzilla, this station was destroyed by Zilla and used as the entrance to the nesting ground inside Madison Square Garden.