The deal was completed after the close of business on 31 July. The move was approved by the Prudential Regulation Authority for the insurance arm and the Financial Conduct Authority for the asset management arm on 26 July.
This had followed the signing of a sale and purchase agreement between two parties and approval from Royal London members.
As part of the move, Co-operative Insurance Society (CIS) must covert to a limited company and change its name to RL (CIS) Ltd.
Chief executive of the Royal London Group Phil Loney said: "Today marks the end of a lengthy and extremely thorough acquisition process. We now begin the process of welcoming new colleague from CIS and The Co-operative Asset Management and integrating the acquired businesses into the Royal London Group."
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Niall Booker, chief executive of the Co-operative Banking Group, said he believed the move was the best outcome for members.
He said: "The transfer of ownership of our life assurance and asset management businesses to Royal London will ensure the continued protection of our policyholders, within a strong, mutual business with the necessary scale and focus on the long-term savings sector. We believe this is the best outcome for our policyholders and members."
Royal London operates through various brands including RLAM, Ascentric and Scottish Life.

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