The Church of England Pensions Board has agreed a £160m buy-in with Aviva covering the previously uninsured pensioner benefits within the Church Workers Pension Fund.
The CofE said the move would reduce the scheme's exposure to investment and longevity risk and also reduces the risk of a deficit emerging.
It said the transaction was a prudent step which was made possible due to strong investment performance since 2019.
It added that more than 92% of Church employers, such as dioceses and cathedrals, whose employees' pensions are in the Church Workers Pension Fund supported a proposal in 2019 to reduce investment and longevity risk if the opportunity arose.
The transaction means all the pensions in the Church Workers Pension Fund, for those who retired before 13 August 2021, are now insured through this buy-in or through a similar buy-in the CofE Pension Board completed in 2013.
Church of England Pensions Board chair Clive Mather said: "The buy-in is good news for employers, members and the Pensions Board in reducing risk for all of us, and helping to secure the pensions of those who have given so much to the Church.
"This transaction is made possible by excellent returns on investments in recent years, and the continued support of the employers."
Aviva head of bulk purchase annuity origination Jamie Cole added: "We're delighted that the trustee of the Church Workers Pension Fund selected Aviva to secure member benefits.
"This has been a very smooth process run by a well prepared and well-advised scheme. The trustees put ESG and responsible investing at the heart of their decision making and so we are proud to be working with the Church of England Pensions Board, given that this is a key pillar of Aviva's purpose."
The CofE Pensions Board acted in its capacity as trustee for this transaction. It was advised by LCP, Linklaters, Mercer and Cardano.