Zoopla agreed to buy price comparison website uSwitch for £160m (€223m, $246m), as the online property broker looks to expand its reach into energy, personal finance, insurance and communications services.
The deal value would rise to £190m based on uSwitch's future performance.
Zoopla, which is the second-biggest property website in the UK after Rightmove, said the combination "would create a single resource where consumers can research, find and manage their home."
"We have always been at the forefront of innovation in our industry and this deal brings together two of UK's best known and fastest growing digital brands as a natural next step towards creating the ultimate platform where consumers can research, find and manage their home," said Alex Chesterman, CEO and founder of Zoopla.
"With the plans we have to develop our combined services, consumers will have a single resource for all their property needs."
USwitch was founded in 2000, and is majority-owned by a division of Lloyds Banking Group. The acquisition is expected to be settled by the end of June.
Zoopla noted that both sites will continue to trade under their separate brands.
"I am immensely proud of everything that we have achieved over the last 15 years and look forward to the next phase of our journey," said uSwitch CEO Steve Weller.
"Consumers need our support now more than ever before and, with ZPG's impressive credentials as an innovative, consumer-empowering business, I am confident that we will be able to help even more people save money on their household bills."