[6] The G operates 24 hours a day between Court Square in Long Island City, Queens, and Church Avenue in Kensington, Brooklyn and makes all stops along the full route.

Since the 2000s, several improvements have been made to the G, including a route extension in Brooklyn and a full-route audit in 2013 that identified solutions for issues on the G service.

[14][15] Additional GG service was provided for the 1964 New York World's Fair, running nonstop between Hoyt–Schermerhorn Streets station and Roosevelt Avenue every 30 minutes between 10 a.m. and 3:30 pm.

[16][19] On January 24, 1977, as part of a series of NYCTA service cuts to save $13 million, many subway lines began running shorter trains again during middays.

As part of the reroute plan, Queens Plaza became the northern terminal for the G train on evenings, weekends, and late nights.

[11][33][34] On December 16, 2001, the 63rd Street Connector opened and Court Square became the northern terminal for the G train during weekdays, while G service was extended to Forest Hills–71st Avenue at all other times, which represented the reverse of the previous pattern.

[16][35] The G was to be truncated to Court Square at all times to make room for the V, but due to rider opposition it was cut back only on weekdays until 8:30 pm.

[16] On July 19, 2012, MTA officials made this extension permanent because it provided more direct connections between Kensington and north Brooklyn.

[9][35] Due to the MTA's financial crisis in the late 2000s, as well as continued capacity issues on the IND Queens Boulevard Line, the G was to be cut back from Forest Hills–71st Avenue to Court Square at all times beginning June 27, 2010.

[40][41] Flood waters from Hurricane Sandy caused significant damage to the Greenpoint Tubes under the Newtown Creek.

[42] Historically, it has connected only Brooklyn and Queens,[35] resulting in many people thinking of the G as the subway system's "outcast"[43] and the "unwanted drunk uncle everyone has.

[51][52][53] The service plan was designed to redistribute Queens-bound passenger loads on the crowded IND Queens Boulevard Line, which ran under 53rd Street while in Manhattan.

The New York Times prematurely described the service plan as "complex and heavily criticized" because it put more crowding on the E train.

[47] In response to complaints from G riders at public hearings about losing a major transfer point to Manhattan-bound trains at Queens Plaza, the MTA agreed to a number of compromises, including installing a moving sidewalk in the passageway between Court Square and 23rd Street–Ely Avenue (now served by the E and ​M trains) on the Queens Boulevard Line.

[35] In addition, a free out-of-system MetroCard transfer to 45th Road–Court House Square on the IRT Flushing Line was created at those two stations.

"[47] However, due to construction on the Queens Boulevard Line, the G train frequently terminated at Court Square even when the published timetable said it ran to 71st Avenue.

"[56] To increase service and reduce waiting time due to the 63rd Street Connector cutbacks, the G would need more trains, but there were not enough cars available in the system.

Still, the overall lack of visual identifiers of train stop points on the platforms, the differing stop points during different times of day, and the location of staircases, transfer passageways and platform benches have been cited as a cause of passengers missing trains or being bunched into single cars.

[59][61][62][63] Save the G!, the Riders Alliance, and other organizations have also lobbied for the creation of new free out-of-system transfers to nearby stations.

[68] A temporary, MetroCard-only transfer between 21st Street and Hunters Point Avenue (along the IRT Flushing Line) was proposed, but not implemented.

[35] However, in July 2005, in response to community pressure, the MTA agreed to re-open an exit to the southwestern corner of South Portland Avenue to the southbound platform of the Fulton Street station.

[71] In 2019, the Court Square station received several new stairways to accommodate increased ridership from L train riders during the reconstruction of the BMT Canarsie Line tunnels under the East River, which started in late April 2019.

It reduced the need for riders from Park Slope and Kensington to make multiple train transfers to get to northern Brooklyn and Long Island City.

[9][16][35] In 2013, at the request of State Senators Daniel Squadron and Martin Malave Dilan, the MTA conducted a review of the entire G route.

[58] The route had been maligned by riders because of its unreliability, and the review recommended a few service changes for the G.[35][59][58] On June 9, 2014, a budget surplus in the MTA allowed these improvements to be implemented.

[58] These improvements also had the additional benefit of being able to accommodate the growing ridership base in gentrified neighborhoods along the line, like Park Slope, Carroll Gardens, Bedford–Stuyvesant, Williamsburg, Greenpoint, and Long Island City.

As a result, riders in Williamsburg, Greenpoint, and Bushwick would need to use the G to transfer to other subway routes that travel to Manhattan.

[75][76] In December 2022, the MTA announced that it would award a $368 million design–build contract to Crosstown Partners, a joint venture between Thales Group and TC Electric LLC, to install communications-based train control (CBTC) along the length of the G route.

[87][88] Local politicians asked the MTA to operate full-length G trains and extend the route to Forest Hills following the partial closures.

[4] The G train is shown in the TV series Girls, as the show's main character, Hannah, lives in Greenpoint (near a stop along the G) and sometimes uses the route.