Sharecast - Capita will manage the pension scheme, one of the UK's largest public sector schemes, from September 2025 in a deal worth £239.0m over a decade.
Under the new contract, Capita (LON:CPI) will modernise pensions administration systems and integrate generative artificial intelligence technology.
The London-listed group said the contract builds on its "strong track record" of successful delivery as a strategic supplier to UK Government, as well as its "depth of experience" operating in the regulated pensions market.
Chief executive Jon Lewis said: "This award is testament to the commitment of our colleagues to design innovative solutions and deliver exceptional customer experience."
As of 0915 GMT, Capita shares were up 2.56% at 18.81p.
Reporting by Iain Gilbert at Sharecast.com