In 1886, a south curve was added to the junction allowing passengers to join the London trains at Harpenden rather than Luton.

Alfred King, station master from 1920 to 1927, committed suicide at age 53 on 29 March 1927 by lying on the rails in front of an express train.

[3] The station has toilets, a newsagent, dry cleaner, taxi office and rank, and a coffee shop.

All four platforms have been extended to support 12-carriage trains, as part of the Thameslink programme; this also required the widening of a road bridge.

Four of these were fast trains between Bedford and Brighton, via King's Cross Thameslink station in central London and Gatwick Airport.

From March 2009, First Capital Connect, in partnership with Southeastern, began running a Luton-Sevenoaks service, which called at Harpenden.