In an announcement today (January 30), L&G's board said it will now look to appoint a successor, either from within or outside the business.
Until a new boss is appointed, which L&G said could take "around a year", Wilson will remain in his post as CEO.
This morning, L&G's share price was down more than 2 per cent. During the course of the past year, it has fallen around 11 per cent.
My decision to retire from the group has been taken with mixed emotions.Nigel Wilson, L&G
Having joined L&G as its chief financial officer back in 2009, Wilson became CEO in 2012.
When Wilson took the top job, L&G was going through a restructure following a merger of its savings and protection businesses as part of its acquisition of platform operator Cofunds.
In its last annual financial results for 2021, L&G's operating profit rose 11 per cent to £2.3bn.
Today, the group said it expects to deliver operating profit growth for 2022 in line with the first half of the year, when it was up 8 per cent.
On his exit, Wilson said: "Legal & General has been a big part of my life and my decision to retire from the group has been taken with mixed emotions.
"I firmly believe we have laid strong foundations to support the next phase of growth for the group, with one of the most talented, collaborative and collegiate management teams in any industry to deliver this."
Wilson, who was knighted last year, has also sat on a number of panels, committees and forums during his time at L&G for the likes of the Bank of England, prime ministers and think tanks.
Towards the end of Wilson's leadership, L&G's UK-based liability driven investment (LDI) arm experienced turbulence after interest rates soared following the "mini" Budget.
One consultant told FTAdviser some of his colleagues were of the belief that everything nearly ended for LDI at the end of September.
L&G has since said it worked closely with pension fund clients to iron out the hedging levels in their portfolios.