The political party raised the donations after it sent out emails in response to the shock announcement.
Labour's fundraising email raised £200,000 in the first 24 hours, according to an email sent on Wednesday.
Both Labour and the Liberal Democrats have welcomed the chance to fight the General Election in seven weeks' time. Both parties voted in favour of the Prime Minister's motion to call the election under the Fixed-term Parliaments Act, which required a two-thirds majority.
At the last General Election the party saw its vote share plummet, as previous supporters abandoned it in favour of the Conservatives. Their share of 57 MPs was reduced to only eight, with leader and former Deputy Prime Minister Nick Clegg stepping down.
However, the Liberal Democrats have been revived in recent months by their stridently anti-Brexit campaign, aiming to target the vote of the 48 per cent of the UK electorate who backed the Remain campaign in the EU referendum.
Since the May 2015 general election the party has doubled its membership to over 90,000, while over 2,500 people joined the party in the immediate aftermath of May's election announcement.
The House of Commons Library reported the Labour party's membership at 517,000 in March, making it the largest political party in Europe. The Conservative party has around 130,000 to 150,000 members, according to estimates.
However, the Conservative party is expected by pollsters to win the General Election comfortably. A voting intentions poll by Yougov after the announcement suggested the Tories will win 48 per cent of the vote, which could translate to Labour losing as many as 56 seats.