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. Trains do not currently serve the Northern City Line in the late evening or at weekends, running instead to London King's Cross. The NLR station was damaged by a V-1 flying bomb on 27 June 1944, however, its main building remained in use until it was demolished in the 1960s during the building of the Victoria line. The original westbound platform buildings remain, as does a small part of the original entrance to the left of the present station entrance. 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.
This station can be confusing as the British Rail Line is referred to as the Northern City Line as is the Northern Line (Northern City Line), neither of which should be confused with the London Overground North London Line. Highbury & Islington has a total of eight platforms, divided between those that are on the surface and those that are deep level: Platform 1 – East London Line services to Crystal Palace, Platform 2 – East London Line services to Clapham Junction, Platform 3 – Northbound Victoria line, Platform 4 – Northbound Northern City Line, Platform 5 – Southbound Victoria line, Platform 6 – Southbound Northern City Line, Platform 7 – Westbound North London Line, Platform 8 – Eastbound North London Line. Platforms 1, 2, 7 and 8 are surface platforms. The entrance resembles a dowdy car-repair facility. The station is in Travelcard Zone 2 and has wi-fi, payphones, lifts, boarding ramps, escalators and a bridge but no toilets.
Connections: Victoria Line. North London Line (London Overground). National Rail. London Buses routes 4, 19, 30, 43, 271, 277 and 393 and night routes N19 and N41 serve the station.