The shocking announcement will help her seek a strong mandate as she negotiates Britain's exit from the European Union.
The snap election would be held on June 8 two years after the last vote and three years before the next scheduled general election in May 2020.
May said she would ask the House of Commons on Wednesday to support her call for an election.
According to British media, May is taking advantage of polls that put her Conservative party approximately 20 points ahead of the Labour Party.
Making the announcement outside 10 Downing Street in London, the Prime Minister voiced her conviction that another election was "the only way to guarantee certainty and security for years ahead."
May said that since her countrymen voted to exit the European Union in June, the country had come together, but politicians had not.
The Prime Minister said Britain's political divisions risk Britain's ability to make a success of Brexit.
"Division in Westminster will risk our ability to make a success of Brexit, and it will cause damaging uncertainty and instability to the country," Prime Minister May said.
At present, her Conservative party enjoys a small majority, with 330 seats in the 650-seat House of Commons.
May said that her government's opponents believe that because her party's majority is so small, her resolve will weaken and that they (opposition) can force them to change course.
May triggered a two-year countdown to Britain's exit from the EU last month. Negotiations to settle exit terms and agree on a new relationship are expected to start soon.
Under Britain's Fixed-Term Parliaments Act, elections take place every five years.
However, the Prime Minister can call a snap election if two-thirds of lawmakers vote for it.
Jeremy Corbyn, the leader of the main opposition Labour Party, welcomed May's decision.
"We look forward to showing how Labor will stand up for the people of Britain," Corbyn said.