Riley and its 14 team members, including three partners and a director, will relocate to Thomas Westcott’s office at Marsh Mills, creating a 55-strong team in Plymouth.
The firm said the move will bring together the “considerable experience and expertise” within the two firms for the benefit of existing and new clients.
Shona Godefroy, managing partner at Thomas Westcott, said: “Joining forces with Riley Chartered Accountants represents our continued growth and investment in Plymouth. It is an exciting opportunity for us to enhance our team and grow our client base in and around this vibrant city.
“Riley is a very well established firm and we already have a strong relationship with the team. Our firms are very like-minded in ethos and approach and, like us, Riley serves a diverse client base.”
Jon Stacey, partner at Riley Chartered Accountants, added: “This is a merger that has been carefully planned for more than two years and we are really looking forward to the benefits that come from combining the two teams and being able to offer a really caring service to our clients.”