Norwich Union is to acquire Select & Protect's (S&P) £24m standard household account.
The move comes after a mutual agreement between S&P and Hiscox to end a
20-year relationship on the book, as the underwriter seeks to concentrate on its core, high net worth business.
The two companies will continue to work together to develop a mid net worth product.
S&P managing director Simon Hood said: "The parting is very amicable. They wish to focus on the mid and high net worth sector, whereas Select & protect is seeking to service the needs of a much wider group of homeowners.
"As a result we need policies more in line with our customer base."
New buildings and contents policies will be underwritten by Norwich Union from 1 November, while existing customers will be transferred by 1 December.
S&P, which specialise in household insurance provided through financial advisers, is planning to use the new relationship to develop a new range of products called Ultima.
Meanwhile, S&P's sister organisation PlusOne Services has launched a white labelling and third party administration service for personal lines products to life companies, IFAs and mortgage clubs.
The scheme will offer financial service companies the opportunity to produce an own-brand product range without incurring huge start up costs.