The deal is subject to regulatory approval.
Royal London said it believes the acquisition will enable it to benefit from the growing later life lending market and widen its scope by referring its clients to Responsible Life advisers.
This deal follows a referral partnership between the two companies in September.
Barry O’Dwyer, group CEO of Royal London said: “Since equity release became a regulated market, accessible through specialist advice, customers can now access good quality products. We believe that later life lending will become a core part of financial planning.
“Our relationship with Responsible Group will allow us to broaden their reach while ensuring existing clients remain supported. Financial advisers have a great opportunity to access support from Responsible Group’s specialist advisers, which will benefit both them and their clients.”
Steve Wilkie, executive chairman of Responsible Group, said: “We are delighted to find in Royal London a partner that truly shares our passion to improve the lives of customers in retirement by giving them straightforward, affordable access to the equity in their homes.
“The investment from Royal London is another exciting chapter in our company’s growth story as we continue to be at the vanguard of the development of the later life lending sector, improving products, and breaking down barriers for customers.”
Wilkie added: “The further commitment of a brand like Royal London to the later life lending market is an important endorsement of the growing role that equity release and retirement mortgages play in responsible financial planning.”