The FTSE 250 outsourcing firm said it had been supporting Peterborough council since 2011 as part of a 10-year partnership providing services including customer services, business support services, shared transactional services, transactional HR and payroll, procurement and business transformation.
The ten-year extension is until 2021 and carries a value of around £105mln.
The firm added that it had signed a two-year extension with Lincolnshire local authority worth a total of £30mln. The contract included the provision of customer services, financial services, IT services and transactional HR and payroll.
With the extension, these services will continue until at least 2022.
Rupert Soames, chief executive of Serco, said the firm had met its key performance indicators across both contracts and had “worked extremely hard to deliver improvements in these services”.
In early trading Tuesday, Serco shares were up 1.6% at 85.5p.