Nearly one in six people (15%) went on holiday by themselves in the 12 months to August, a survey by travel trade organisation Abta found.
This is up from 12% in 2017 and 6% in 2011.
Having the opportunity to choose what they want to do is the most common reason why people travelled alone, with more than three in four (76%) saying this was the case - rising to 92% for people aged 35-44.
This was followed by the chance to “take some time out” (63%) and visit a new destination (37%).
The chance to meet new people has become less of a priority, with fewer than a third (31%) saying that was why they chose a solo trip compared with 41% last year.
Abta chief executive Mark Tanzer said many people holiday alone to boost their mental health.
He told the organisation’s annual convention in Seville, Spain, that one of the most common reasons for going on holiday is “getting away from everyone”.
Mr Tanzer added: “The holiday has become a major part of our strategy for staying sane.”
Factors attributed to the increase in people holidaying alone include greater availability of wi-fi making it easier to keep in touch with people back home, and the growth of smartphones and travel apps which means navigating the world is less daunting.
Travel firms are expanding their options for people who want to travel alone, including STA, Saga, G Adventures and Costsaver.
Many companies have scrapped single supplements in a bid to attract customers.
Costsaver has seen a 37% increase in UK guests travelling solo so far in 2018 compared with the same period last year.
The firm expects this trend to continue and is expanding its range of guided independent trips next year to include destinations such as India, Japan, Vietnam and Cambodia.
Mr Tanzer said: “Going on holiday by yourself means you don’t have to compromise on your choice of destination, your itinerary or the activities you take part in.
“Whether they’re single or just want some ‘me time’, people now have an incredible choice of holidays and destinations to choose from and it has become so much easier to explore the world.”
Some 22% of solo travellers visited Asia during the last 12 months, compared with an average of 15% among all types of holidaymakers.
One in 50 (2%) went on holiday to the Arctic or Antarctica - more than twice the number who travelled with friends or family.
Abta commissioned a survey of 2,001 UK adults for the research.
The North West saw the biggest increase in people holidaying alone during the past 12 months, up from 9% to 18%.
The second largest uplift was in Wales, which saw a rise from 6% to 14%.