The station developed on three contiguous sites: The West Coast Main Line (WCML) station was opened by the London & North Western Railway on 1 September 1866 to replace the London and Birmingham Railway's Willesden station of 1841 which was 0.5 miles (0.80 km) to the northwest. Passenger services ended in 1962 when the platforms were removed during electrification of the WCML to allow the curvature of the tracks to be eased. Later the bridges for the North London Line (NLL) were rebuilt. The High-Level station on the NLL was opened by the North London Railway in 1869 on a track crossing the WCML roughly at right angles. The 'Willesden New Station' or Low-Level station on the Watford DC Line was opened in 1910 to the north of the main line with two outer through platforms and two inner bay platforms at the London end. The name derives from the Anglo-Saxon Willesdune, meaning the Hill of the Spring, and a settlement bearing this name dates back to 939 AD. The Domesday Book of 1086 records it as Wellesdone. However, on 19th century maps of the town such as those from the 'Ordnance Survey First Series', the town is shown as Wilsdon.
There are no platforms on the West Coast Main Line, which is separated from the low-level station by the approach road to Willesden Depot which lies immediately south-east of the station. The high-level (HL) station consists of an island platform rebuilt in 1956, with faces as platforms 4 and 5, which are roughly at the level of Old Oak Lane to the west of the station, serving the NLL and the West London Line; some trains on the latter reverse in a central turnback siding on the NLL to the east of the station, this opened in 2011. Both platforms have been extended across the DC line to accommodate 4-coach class 378 trains. The HL station previously had a third platform on the eastern side which was used by services to/from Earls Court. There is another turnback siding further east which was previously used; it was laid in the late 1990s to allow Royal Mail trains to reach the Royal Mail depot at Stonebridge Park. The low-level station, at the level of the area to the south, is an Edwardian island platform, with outer faces as platforms 1 and 3 and northern bay platform bay as platform 2, the southern bay now has no track. NOTE. Willesden Junction is on the North London, West London and Watford DC Overground Lines; please find out the destination of the train before boarding. The station has wi-fi, boarding ramps, lifts and no toilets.
Connections: Bakerloo Line. Watford DC Line and West London Line.The station area is served by London Buses routes 18, 220, 228, 266, 487 and night route N18.