The current station derives from two earlier stations. The first, which was on the same site, was an impressive Victorian-gothic building, with a drive-in forecourt, built in 1872 by the North London Railway (NLR). The second station, on the opposite side of Holloway Road, was opened on 28 June 1904 by the Great Northern & City Railway (GN&CR) on its underground line, between Finsbury Park and Moorgate. This line and stations were operated by the Metropolitan Railway and its successors from 1913 until 1975 when the line, by then called the Northern City Line, was transferred to British Rail. The route is now operated by Great Northern. Today's single-storey structure was built in the 1960s for the opening of the Victoria line on 1 September 1968 and is the entrance for all lines. When the escalators to the deep level platforms were opened the GN&CR station building was closed. Its disused entrance remains and was refurbished externally in 2006 – it houses signalling equipment for the Victoria line.
The Victoria line was built to give as many interchanges as possible with Underground and British Rail lines, with, wherever possible, cross-platform connection between different lines heading in the same direction. To this end at Highbury & Islington the northbound Northern City Line platform was reallocated to the southbound Victoria line to give a direct link between the two southbound platforms; a new northbound platform was constructed for each line; the northbound running NCL tunnel was diverted to its new platform; and the southbound Victoria tunnel was joined to the old northbound NCL tunnel. Platforms 3 to 6 are deep-level platforms. Platforms 3 and 5 are used for services on the Victoria line; 4 and 6 are used for Great Northern services on weekdays only. The station has boarding ramps, lifts, escalators payphones and wi-fi. NOTE: Only the Overground and National Rail are wheelchair accessible.
Connections: National Rail. London Overground. London Buses routes 4, 19, 30, 43, 271, 277 and 393 and night routes N19 and N41 serve the station.