Although Number 10 has previously denied any intention to hold an early election, May now says it is in the national interests.
She is hoping to secure the government’s position ahead of the Brexit negotiations, which she says will strengthening its bargaining power with the European Union.
“There should be unity in Westminster but there is a division, the country is coming together but Westminster is not," she said on the steps of Downing Street today.
The prime minister said Labour, the Liberal Democrats and the SNP where jeopardizing the work needed to prepare for Brexit and urged the public to vote for the Conservatives to “guarantee stability and certainty”.
She accused other parties of "game-playing" and said if an election was not held now that would continue.
May described this time as a “one-off chance” to affirm her mandate.
Tomorrow she will table a motion calling for the early election, which will require a two thirds majority in the House of Commons.
The prime minister triggered Article 50 to start the process of leaving the EU on 29 March, with the aim of the process taking two years.
Jeremy Corbyn, leader of the Labour opposition, said: "I welcome the prime minister’s decision to give the British people the chance to vote for a government that will put the interests of the majority first.
"Labour will be offering the country an effective alternative to a government that has failed to rebuild the economy, delivered falling living standards and damaging cuts to our schools and NHS."
He said in the last couple of weeks, Labour had set out policies that offer a "clear and credible choice for the country". "We look forward to showing how Labour will stand up for the people of Britain."
Tim Farron, leader of the Liberal Democrats, stated: "This election is your chance to change the direction of our country.
“If you want to avoid a disastrous Hard Brexit. If you want to keep Britain in the single market. If you want a Britain that is open, tolerant and united, this is your chance."
He added: "Only the Liberal Democrats can prevent a Conservative majority.”
Caroline Lucas, Green party’s co-leader, said: "Britain is at a crossroads – and today’s announcement means that people are rightly given a say over the direction this country is going to take.
"Only the Green party offers a bold, positive vision for a different kind of Britain. At this election we will stand for an economy that works for everyone, not just the privileged few; a Britain that’s open to the world and the protection of our precious environment.
"We will stand up to the politics of hatred and division that is scarring our communities and give people across the country a chance to vote for a better Britain."
Paul Nuttall, leader of UKIP, said: "We believe that the prime minister’s decision to call this election is a cynical decision driven more by the weakness of Corbyn’s Labour Party rather than the good of the country.
“We are in the midst of Brexit negotiations so this election will provide a perfect opportunity for the 52% to vote for Ukip - the only party wholeheartedly committed to a clean quick and efficient Brexit.”