Nine Post Office counters in Spar convenience stores in Tayside and Fife will close in the next year.
Dundee-headquartered Spar Scotland said the decision followed 18 months of negotiation with Post Office Limited.
Spar said the move to shut loss-making counters would help ensure the stores continued to operate.
The Post Office has expressed its concern at elderly accessing its services.
Spar Post Office counters to close
A total of 31 Post Offices counters in Spar will close with 17 remaining open.
Six of the closures are in Fife – St Andrews, Newport on Tay, Balmullo, East Wemyss, Ladybank and Thornton.
Luncarty and Stanley in Perthshire and Menzieshill in Dundee are on the closure list.
Five counters will close in Aberdeen – Kincorth, Torry, St Machar, Clifton Road and Northfield.
The closures will take place over a six month period beginning in August.
Spar statement on Post Office decision
Spar has given an assurance the affected convenience stores will remain open.
It also said staff working in its Post Offices counters will move to other positions.
A spokesperson said: “To ensure our continued operation in communities across the region, 31 stores will no longer be able to offer Post Office services.
“This decision has been carefully considered and comes after 18 months of negotiations with Post Office Limited.
“It is unfortunate that we find ourselves in the position of having to change the services we offer over the next six months.
“This is representative of the industry-wide pressures on retail outlets as we evolve to keep up with changing consumer habits.”
Impact on elderly
Post Office said it was concerned about the impact on older customers.
“Post Offices play an important role in the heart of local communities across Scotland and we are disappointed that today Spar Scotland announced the counters they operate on our behalf will close at a number of their stores,” the spokesperson said.
“We have worked closely with Spar Scotland to help keep open essential Post Office services for their customers.
“At certain locations, there are nearby alternative Post Office branches.
“But we recognise that for some particularly older people they may not be easily accessible.
“We will look for replacement solutions both on a temporary or permanent basis for those branches that close.
“We are awaiting formal confirmation about the timescales for the affected branches before we inform local communities impacted.”