The group, which is headquartered in Zurich, said its Admin Re division will buy Guardian to bolster its position in Britain as a consolidator of life funds that are closed to new business.
Swiss Re fought off competition from a number of suitors to buy Guardian from its private equity owners Cinven.
Phoenix - Britain’s largest closed fund consolidator - last week confirmed it was in talks over a possible takeover of Guardian.
Guardian manages pensions, savings and protection policies for more than 900,000 policyholders across the UK and Ireland.
The deal will boost Admin Re’s UK business to more than four million policies, up from 3.4 million currently, and increase Swiss Re’s overall assets under management by £12.5bn, or 15 per cent.
Michel M Lies, group chief executive at Swiss Re, said: “This acquisition is an excellent opportunity for Admin Re to further enlarge its successful business and diversify its portfolio.”
Bob Ratcliffe, chief executive of Admin Re, added: “Admin Re has an expert team and the infrastructure in place to ensure we can bring the benefits of scale that make a closed life book consolidator successful.”
He said the group will continue to eye further acquisitions in the UK closed life sector.
The Guardian deal is expected to complete in early 2016.
The takeover comes amid a spate of consolidation in the life and pensions sector as it grapples with major changes following reforms announced by Chancellor George Osborne in last year’s Budget.
New pensions freedoms, introduced on April 6, mean that instead of being required to buy an annuity with their pension pot, people aged 55 and over have more flexibility to take their pots how they wish.
Other major deals in the sector have included Aviva’s £5.2bn takeover of Friends Life, while Just Retirement and Partnership Assurance recently announced plans to merge.