The sale comprises its (non-platform) investment and pensions business as well as SunLife, its direct protection business.
The sale of Axa's entire UK Life & Savings business is expected to total €0.8 billion.
Over the last five years, AXA Wealth has more than tripled its assets under management from £15 billion to over £46 billion through its business portfolio.
SunLife specialises in over-50 protection and achieved £152 million gross written premiums in 2015.
Earlier this month, Standard Life acquired AXA Portfolio Services Limited (trading as Elevate), making Standard Life the third largest adviser platform with combined assets under administration of £36.4bn.
Paul Evans, CEO of AXA UK & Ireland, said: “I’m pleased to confirm the sale of the remaining part of our UK Life and Savings businesses to Phoenix Group Holdings.
“I would like to warmly thank the UK life & savings teams in AXA Wealth and SunLife who have accomplished so much over recent years. They can be very proud of what they have achieved, and I wish them all the very best for the future.”
