It is served by the L train at all times, which is shown in medium gray on the New York City Subway map and on station signs.

It is double-tracked along its entire length, except for short stretches of layup track in Manhattan and Brooklyn.

[3] The current line is a two-track subway from its Manhattan terminal to Broadway Junction in the East New York section of Brooklyn, with the exception of a short stretch at Wilson Avenue where it is a double-decked structure with the southbound track outdoors directly above the indoor, ground-level northbound track.

There are no express tracks on the Canarsie line; thus, all trains run local service throughout their route.

[3] However, in the past, express service has been run between Lorimer Street and Myrtle Avenue by skipping stops via the local tracks.

At the next station, Livonia Avenue, the Livonia Avenue Elevated of the IRT New Lots Line passes overhead, and just beyond this point is a single track connection to the Linden Shops, which is now a track and structures facility.

[6]: 57  All platforms on the Canarsie Line are at least 518 feet (158 m) long, but only one station, Sixth Avenue, can accommodate 600-foot-long (180 m) trains without the need for extensions.

North of New Lots Avenue, the line served as part of the New York, Brooklyn and Manhattan Beach Railway; the B&RB owned the section of that line between Jefferson Street and East New York, though this section was solely operated by the NYB&MB.

The East New York terminus was extended several blocks along a section of line formerly used for "East New York Loop" service to the Fulton Street Elevated and the Broadway Elevated (now the BMT Jamaica Line), at a point known as Manhattan Junction (now Broadway Junction).

The expansion extended south to the point at which the Canarsie and Fulton Street Elevateds diverged, including a six-track, three-platform station at Atlantic Avenue.

[12] It was closed by 1973[13] as part of the Flatlands Industrial Park project, which was built on either side of the ground-level Canarsie Line.

[15] In late 1915, the Public Service Commission began receiving bids for the construction of the 14th Street Line.

In 1922, Mayor John Francis Hylan blocked some construction contracts, claiming that the costs were excessively high.

[36] The line collected 9,196 fares in its first day of operation, which constituted its entire ridership for the fiscal year ending June 30, 1924.

From Montrose Avenue, it would curve east under McKibbin Street, private property, and Harrison Place.

[38] In September 1924, the BOT approved the remaining section of the route between Eldert Street and Broadway Junction in East New York.

East of Eldert Street, the route would turn south to a ground-level alignment parallel to the LIRR's Bay Ridge Branch, then run southeast in a tunnel underneath private property to the intersection of Eastern Parkway and Bushwick Avenue, where it would emerge onto a ramp leading to the existing Canarsie elevated.

[39] An ornamental viaduct over Bushwick Avenue and Eastern Parkway was removed from the original plans due to opposition from property owners who called it a "Chinese wall".

[44] Another delay occurred in November 1925 regarding the alignment of the 14th Street/Eastern Line along a three-block section from Cooper Street to Central Avenue, which was to parallel the Bay Ridge Branch.

[46] On July 14, 1928, the line was extended further east beneath Wyckoff Avenue and then south paralleling the Bay Ridge Branch to a new station at Broadway Junction, above the existing station on the Broadway Elevated (Jamaica Line).

[50] Express service operated along the line along the local track, skipping all stops between Myrtle Avenue and Lorimer Street.

[55] In June 2005, the Canarsie Line ran full-length 480 feet (150 m) trains with a single operator on weekends.

[55] In January 2016, the BMT Canarsie Line between Bedford and Eighth Avenues was proposed for a partial or full shutdown so that the MTA could repair tunnels damaged by Hurricane Sandy in 2012.

[60] The repairs are slated to start in April 2019 and would replace damaged communications, power and signal wires, third rails and tracks, duct banks, pump rooms, circuit breaker houses, tunnel lighting, concrete lining, and fire protection systems.

[64][65][66] To provide alternate service, the MTA devised preliminary mitigation plans in which it proposed adding shuttle bus, ferry, and subway service; adding bus and high-occupancy vehicle lanes; extending train routes; and providing free or improved transfers.

[67] The MTA named Judlau Contracting and TC Electric as the project's contractors on April 3, 2017.

[68]: 41  In June 2018, as part of a lawsuit settlement, additional changes were made to the shutdown mitigation plans.

[72] On April 26, 2020, New York governor Andrew Cuomo announced the completion of the project, months ahead of schedule.

In 1936, due to the institution of new lightweight subway-elevated equipment, a new rush-hour-only service was inaugurated from Eighth Avenue and 14th Street to Lefferts Boulevard at the east end of the Liberty Avenue Elevated (the continuation of the Fulton Street Elevated).

The Eighth Avenue–Canarsie route was given BMT marker 16, and trains running to Lefferts Boulevard usually were marked as 13.