New service will be available later this year online and in-store.
The Post Office has announced it will be teaming up with EE to launch its first ever mobile phone network.
The low-cost service will be initially launched in 50 branches, as well as through the Post Office website and over the phone, ahead of a wider rollout later in the year across the rest of the 11,500 Post Office branches across the country.
The Post Office already provides home phone and broadband deals to around 500,000 customers across the UK, and is seeking to expand this as it becomes the latest high-street chain to offer mobile services.
"This is part of Post Office’s ambitious commercial vision to drive growth in its financial and home services businesses while underpinning its status as the number one mails retailer," the group said in a statement.
Martin George, chief commercial officer at Post Office, said that the news was "a fantastic vote of confidence in the Post Office brand", which sees more than 17m customer interactions per week.
The group recently carried out a survey which found that one in three people intended to move away from one of the mainstream providers to find their next mobile service.
"We believe we are in an ideal position to offer a genuine alternative with over a third also saying they would consider us as their mobile provider," George said.
"Launching our own mobile service, using EE’s network, is a significant milestone in the Post Office’s journey of change and a testament to our continuing efforts to offer more essential services for our customers."
The new network will be powered by EE MVNA Transatel, and is the latest in a series of MVNO contract wins for EE after it recently helped launched mobile networks for both Asda and BT.
BT will rent space on EE’s masts and offer 4G smartphone connections package together with broadband, landline calls and pay TV services.