It claimed that just 19% of UK adults now book their
holidays on the high street compared with 57% in
The travel search engine said its online survey of over 12,000 adults, including 1,005 from the UK, revealed that 79% of people now book their holidays online, 50% via travel agents' websites, 47% direct with airlines and hotels, and 24% via online travel search engines.
One in 10 book on the telephone, it said. Some people said they used more than one method.
Loella Pehrsson, Kayak regional director UK, Ireland & the Nordics, said: "The research is a worrying signal for high street travel agents but isn't entirely shocking.
"Given the internet allows you to not only shop around, but browse and book holidays from the comfort of your own home, it's no surprise that Brits are increasingly choosing this option over high street travel agents."
However, ABTA said its latest consumer survey showed that high street bookings were holding steady and it pointed out that Kuoni has just opened new stores.
The most recent ABTA annual Holiday Habits report showed that people are more likely to use agents to book higher value, last-minute and longer holidays, but as many agents have both shops and websites it wasn't able to stay whether people prefer to book online or face to face.
ABTA did admit, however, that consumers were more likely to book city breaks and domestic holidays directly with the service provider.
Kayak claimed that while 77% of those booking online still use computers, 8% are using smartphones.
Over half (53%) check in for flights online, compared to just 22% in 2006, and 16% now use mobile boarding passes.
For inspiration, one in five use social media and 15% look at blogs (rising to 40% and 33% respectively for those aged 18-24) - more than double the figure 10 years ago.
However, the additional sources make the planning process more complex, with 35% saying they spend more time planning their travel than they did a decade ago.