More than one in four transactions made with Hotels.com are now booked via its app, with downloads reaching over 40 million.
UK consumers have the highest mobile share in western markets with 41%, compared to the global average of 30%.
The overall increase in UK mobile app bookings made over the past year has risen by 120%.
Mobile traffic exceeded 50% during the last few months of 2014 for same day or next day stays, including city breaks, beach holidays and backpacking stays.
The most popular destinations booked by UK travellers using mobile devices in 2014 were New York – at an average price of £170 – Las Vegas (£90), Paris (£124), Dublin (£88) and Amsterdam (£105).
Spokeswoman Carolina Annand, said: “It is fascinating to see how many UK travellers are using our app to make bookings.
“In a world where time is of the essence, and spontaneous trips occur more frequently, it seems that app bookings are the way forward for ensuring a safe and speedy booking experience, both of which we guarantee when using the Hotels.com mobile technology.”