The terms of the deal have not been disclosed.
In May Tui formally announced its intention to sell the business.
A spokesperson for Tui said: "We can confirm that the sale as it was announced in May 2015 has been completed early October. Since May LateRooms.com was ’held for sale’ as Tui Group is focusing on the integrated tourism business. However, both parties agreed not to disclose financial or any further details."
LateRooms was setup in 1998 by brothers Steve, Paul and Tony Walsh.
Private equity firm ECI funded the buy-out of LateRooms in December 2004 before it was sold to First Choice for up to £120m in 2006.
LateRooms was part of Tui’s LateRooms Group, which also included AsiaRooms and MalaPronta.
AsiaRooms was closed earlier this year and Tui has now confirmed that MalaPronta will also be shut as no buyer could be found.
"Customers are redirected to the call centre if they have a booking, others will see a notice on the webpage. All bookings are being honoured," a spokesperson said.
