The DB2/4 Mk II model, introduced in 1955, offered an optional large-valve, high compression (8.6:1) 165 hp (123 kW) engine. Other changes included small tailfins, bubble-type tail lights as on the Morris Minor, and added chrome. The bonnet horizontal split line was also changed from door sill height to a line carried backwards from the top of the front wheel arch.

A 2-seat Fixed Head Coupé (FHC) was new, in addition to the continued Drophead. 34 of the 199 Mark II models used this new coupé body, which was the style chosen by David Brown for his own car. Three Mark II chassis were sent to Carrozzeria Touring in Italy to be bodied as Spider models. Touring would later help Aston with the Superleggera design of the DB4.

One significant behind-the-scenes change for the Mark II was the relocation of coachbuilding responsibilities from Mulliner's of Feltham to Tickford's works in Newport Pagnell. Brown had purchased Tickford in 1954 and would move all of Aston Martin's operations there with the start of DB4 production.