The move will be a blow to specialist insurance firm Hextall Erskine. White is head of the commercial dispute resolution department and is regarded by many as the hub of the practice.
He is also taking fellow partner Davina Haydon with him. Haydon has been with the firm for a decade.
White is well known for his professional indemnity work for the construction industry. But while he will continue to work for architects and engineers at his new firm, he will be based at the Leadenhall Street office and will focus mainly on insurance and reinsurance.
Reynolds is known for its work for the Lloyd's syndicates. But Reynolds insurance partner Tim Brown hopes that White's appointment will help the development of the firm's company work as well.
He says: "We're constantly looking out for expert practitioners to join us. Stuart and Davina bring with them a wealth of experience and strength in the companies market that complement our existing strengths."
White has worked on a number of high-profile cases, including the personal accident insurance claim following the death of media giant Robert Maxwell in 1991.
Haydon works in professional indemnity but also specialises in claims involving contaminated land as well as fire losses.
Despite being a partner at Hextall Erskine, Haydon will not join the Reynolds partnership. Brown says that the difference in the size of the two firms played a part in her not taking partnership. He says: "We have no problem with Stuart's abilities and proven track record. But when you take on a small venture like this [your lawyers] have to be commercially viable and you have to see how they develop."
Hextall Erskine is one of the UK's leading insurance players and the 29-partner firm is particularly well known for its construction work. Its clients include GE Lloyd-Roberts & Others, Wren Managers and First Assist.
White declines to comment on his reasons for leaving other than to confirm that Reynolds will provide "fresh challenges and new opportunities". He also refuses to discuss whether he will be taking clients with him.