A silhouette of the Houses of Parliament and Elizabeth Tower containing Big Ben, centre, at dusk, in Westminster, London, Tuesday April 18, 2017.
But Mr Corbyn dismissed her argument that she needs a fresh mandate to deliver Brexit, and said it was "extremely interesting" that she had chosen to call an election as the Crown Prosecution Service prepares to decide whether to press charges against a string of Tory MPs over allegations relating to 2015 general election expenses.
Mrs May used her speech to praise MPs after 522 voted in the Commons for the early election, with just 13 against.
"Much of the media and establishment are saying this election is a foregone conclusion. It is about the crisis her Government has plunged our National Health Service into, the cuts to our children's schools which will limit the chances of every child in Britain, four million of whom now live in poverty".
There was never any real doubt about Mrs May securing the backing needed to go to the country, with both Labour's Jeremy Corbyn and Liberal Democrat Tim Farron saying they welcomed the election - though Scottish National Party MPs abstained in the vote.
He said Mrs May's U-turn on her previous insistence that she would not call a snap election showed she could not be trusted.
Since being fired by Theresa May, Osborne has earned lucrative speaking fees and taken on an advisory role for American investment giant Blackrock.
"The election gives the British people the chance to change direction".
"Vote for strong and stable leadership this country needs. Because when we win, it's the people, not the powerful, who win", he will say.
May formally notified the European Union on March 29 of Britain's intention to leave, and has said she is confident of reaching a deal on the terms of withdrawal in the two years available.
She said the early ballot would strengthen Britain's negotiating hand with the 27-member EU.
European Commission spokesman Margaritis Schinas said that "the real political negotiations on Article 50 with the United Kingdom will start after the elections foreseen for June 8". Give me the mandate to lead Britain.
Theresa May kicked off seven weeks of campaigning on Wednesday with a promise of strong and stable leadership after MPs overwhelmingly backed her call for a general election on June 8th. However, the attacks on her decision continued hours later tin the Commons.
One broadcaster, ITV, said it planned to hold a debate with or without the prime minister. Demmer said Wednesday: "The German government assumes that the negotiations can be continued without disruption".
"They want to unite together to divide our country and we will not let them do it".
She said on Tuesday she had "reluctantly" come to the decision to call for an early election because of political division in Westminster, criticizing opposition parties for trying to thwart her plans for leaving the EU.
He added: "She could also become more unbending; we don't know".
Britain's prime minister has defended her decision to seek a snap election.
Labour leader Jeremy Corbyn was the first to mention the decision, opening his remarks by saying: "We welcome the general election, but this is a prime minister who promised there wouldn't be one, a PM who can not be trusted".
May said that opponents were intent on "frustrating the Brexit process", even after Parliament authorized talks with the EU. "It's about ... getting the right deal from Europe", May said.
Parliament will vote Wednesday on holding a June 8 election. The Lib Dems now have just nine seats in Parliament. An early ballot will give the next leader more time to implement Brexit before another election.