Peterborough-based Budget Group has bought Century Insurance Centres and the personal lines business of Marshall Arnott.
The double acquisition means the combined organisation now handles some 430,000 motor and household policies, making Budget the UK's 17th largest broker.
Budget is predominantly call centre-based, whilst Century and Marshall Arnott maintain a high street presence.
Chief executive of the merged business, Peter Winslow, said: "We are very excited about the future possibilities for the enlarged group.
"We share the same vision for the business over the next three to five years and look forward to fully implementing this merger."