She criticised opposition parties for opposing the government’s Brexit plans in enacting the process which was decided with 51.9% to 48.1% majority.
May had originally vowed not to undertake an early election when she won the Conservative leadership contest, but admitted she had “reluctantly” come to the decision.
The move will require a two-thirds majority in the House of Commons to overturn the Fixed-term Parliaments Act introduced as part of the previous coalition government.
May said she would go to the House of Commons tomorrow to begin that process.
She challenged the opposition parties to support the vote and prove they were not opposing government just for the sake of opposing it.
Opposition leader Jeremy Corbyn welcomed the move.