AA, a private equity-owned motoring services firm, and holidays firm Saga Holdings Ltd have won permission from the European Commission for a joint venture combining their operations.
The two will create a British group worth £6.15 billion with 11,100 employees.
Saga sells financial products and holidays to people over 50.
The AA will sell its traditional breakdown assistance and car-related services to Saga's 2.5 million customers, while Saga can offer financial services, cruise liner trips and health club membership to the older segment of the AA's 15 million members.
The transaction was put together by the businesses' main owners Permira , Capital Partners, and Charterhouse Capital.
The two firms will operate separately.