A man got into the delivery car while it was parked on Chetwynd Park, Rawnsley, and drove off while the driver was delivering goods at around 7.05pm on Tuesday.
The vehicle, a silver Seat Leon, took a left turn onto Littleworth Road and left the scene in the direction of Cannock.
The thief is described as white, tall and of slim build, roughly in his mid-20s, with dark clothing.
Police are conducting inquiries locally and reviewing footage at the scene at the time of the incident.
Anyone who witnessed the incident or those with CCTV or dash-cam footage is asked to call 101, or contact police via Facebook or Twitter, quoting incident 644 of May 10.
Alternatively, contact Crimestoppers anonymously on 0800 555111 or at crimestoppers-uk.org