The branch, which has been closed since January, re-opened on Monday (March 13) under new management at the previous location of Harvey Road, Aylesbury.
The shop shut due to the closure of the Midcounties Co-op store.
The opening hours will be Monday to Friday: 9am to 5.30pm; Saturday: 9am to 12.30pm.
Zoe Hall, Post Office Network Provision Lead, said: “We are delighted to be restoring Post Office services to the Harvey Road area of Aylesbury as we know how important a Post Office is to a community.”