Jimmy Young threatened staff at Co-op stores in Midsomer Norton and Timsbury.
The first incident, at about 9pm on July 21, saw Young enter the shop, produce a handgun and threaten a member of staff. He made off with a quantity of cash and made off in a car stolen from South Bristol.
The second robbery occurred at about 7am on August 10 in Timsbury, where he threatened two employees in a similar fashion. He again fled with a quantity of cash, this time in a vehicle stolen from Bradley Stoke.
Forensic evidence found at the scenes confirmed Young was linked to the two robberies and firearms officers successfully arrested the 46-year-old on in Pensford 10 days later.