HotelsCombined has ended 13 years as an independent business following a deal to sell to Booking Holdings.
Terms of the acquisition have not been disclosed. The sale has been approved by the shareholders of HotelsCombined and it is expected to close later in 2018.
The accommodation metasearch site, based in Australia, is best known for its growth and presence in Asia Pacific - a market where new stable mate Kayak has operated for a number of years.
HotelsCombined will become a subsidiary of Kayak following completion of the deal.
CEO of Booking Holdings, Glenn Fogel, says the acquisition will play a part in its ongoing program to "expand our worldwide metasearch strategy".
Alongside a strong consumer-facing business, HotelsCombined has a sizeable affiliate strategy where it powers all or part of the hotel search capability of 18,000 other brands.
Two of those sites are Kayak and Momondo, the European metasearch site bought by Booking Holdings in early-2017 for $550 million.
Earlier this year, HotelsCombined outlined a strategy to adapt the product to suit business travel requirements.
The company is currently headed by CEO Hichame Assi, who joined the company in late-2009 as its head of international strategy and online marketing, before taking over the top job in July 2016.
He says: "We've always been inspired by the entrepreneurial culture of Booking Holdings brands and are excited to be joining the family.
"Operating under the KAYAK umbrella will strengthen our proposition to both customers and partners with greater scale, product breadth and innovation."