The MP for Filton and Bradley Stoke attended the branch launch in Rodway Road at noon on Friday.
The new branch within the Spar Store restores post office services to Patchway following the closure of the former branch in 2009.
The branch will provide customers with an on-site convenience store providing the opportunity to carry out a range of shopping under one roof, access for wheelchair users and parking directly outside.
Mr Lopresti said: “Local services are vital in creating a sense of community.
“I am delighted that the service is up and running again in Patchway and I hope that local residents will continue to support this essential service.”
Newsagents Capper & Co said: “We are delighted to have the opportunity to reopen the Patchway branch of the post office, it’s been a long time coming.
“We are also in the fantastic position to have three of the employees from the old Patchway post office working for us, so for the customers it will just be like old times.”