The Prudential Regulatory Authority (PRA has approved Royal London's acquisition of the Co-operative Banking Group's fund management and life insurance businesses.
The news comes after 95% of members at a Royal London extraordinary general meeting held in June approved the £219 million purchase.
The deal, which was announced in March, is expected to go through before the summer is out. It will increase Royal London's customer base by around 2 million and its funds under management from £50 billion to £70 billion.
The Co-op is selling the businesses in bid to bolster is capital position amid growing regulatory pressure.