Laterooms.com had been in talks with two other agencies about its advertising but told Campaign earlier this month that these discussions stopped short of a formal pitch.
Mother is now tasked with creating an integrated campaign, including TV work, for the brand, which has a seven-figure marketing budget for the first phase of its campaign.
Mark Waites, one of Mother’s co-founders, said: "Laterooms.com have a brilliant energy and want to make great work. What’s not to like?"
Laterooms.com previously used BMB for its advertising. MediaCom is the client’s media agency.
At the beginning of the month, TUI sold Laterooms.com to Cox & Kings in a deal reportedly worth £8.5 million.
Georgina Crosswell, the head of marketing at Laterooms.com, said: "We’re absolutely delighted to be working with Mother. The team there really impressed us with their strategic approach and creative ideas, and we’re raring to get stuck in to developing a stand out campaign that captures the brand’s position and unique personality."