Her predecessor David Cameron regularly holidayed in Cornwall, but also went to foreign destinations including the Canary Islands, Italy and Portugal.
Mrs May lists walking as one of her hobbies and has spoken of doing "a lot of quite strenuous walking up mountains in Switzerland" with her husband.
She is due to return to the UK on 24 August.
Number 10 has described the prime minister's trip as a holiday and has not said whether she will hold any talks with Swiss leaders during the visit.
Despite being in the heart of Europe, Switzerland is not an EU member or a member of the European Economic Area, but signed its first free trade agreement with the EU in 1972.
In 1999 it signed an agreement on freedom of movement with the EU, and is an associate member of the Schengen passport-free area.
It is currently embroiled in long-running talks with the EU over how to implement a 2014 referendum result in which the Swiss people backed limiting immigration through quotas, including EU citizens.
Switzerland has also been a holiday destination for German Chancellor Angela Merkel, who fractured a bone in her pelvis in a cross-country skiing accident in the country in 2014.
Mrs May has previously said that she loves holidaying in Switzerland because she can get some "peace and quiet".
She said she and her husband Philip had "discovered the joys" of walking in the country "quite by chance".
In a piece for the Daily Telegraph in August 2007, she said: "We first visited the country about 25 years ago but spent most of the time in Lucerne.
"On a return trip, we decided to go walking, enjoyed it and gradually began doing more adventurous hikes.
"We have been going back ever since and have walked all over the country."
Mrs May said in the piece that her two favourite areas are Zermatt and the Bernese Oberland, which are both "fantastic for walking".
She added: "If you're a keen walker, Switzerland is a wonderful summer destination: the views are spectacular, the air is clear and you can get some peace and quiet."
Prime Minister Theresa May is to take a summer holiday in Switzerland, Number 10 has announced.