The store was taken over by Harj and Bill Dhesi in November last year.
After seeing the shop through the busy Christmas period, they took the decision to close in February this year for a full re-fit.
Mayor of Stevenage, Cllr Jim Brown, cut the ribbon at the official reopening on Friday, August 2.
Postmistress, Harj Dhesi, said: “When people see all the changes that we have made the reaction is ‘wow!’
“We removed everything and started from scratch. The whole store looks completely different now – very modern.
“There are lots of new retail offerings with bread baked in store, hot food including Rollover hotdogs, fresh sandwiches, Costa coffee, milkshakes and slushies.
“The Post Office has got busier too. There have been several local bank branch closures and people can do their personal and business banking here.
“As well as the traditional Royal Mail and Parcelforce services, we also have many more courier services for delivery and collection – Evri, Amazon, DPD and DHL. Customers like the greater choice.
“Many staff who worked at the previous store continue to work here, so there are still lots of familiar faces. They are a great team and we have taken on more staff as the convenience store and post office are now so busy.”
Symonds Green Post Office is open Monday to Friday, 8am to 8pm and 9am to 3pm on Saturdays and Sundays.
The Nisa Local is open daily from 7am to 10pm.