Jeremy Corbyn has been elected as the new leader of the Labour Party.
He's now in charge of the second largest party in parliament, after he won almost 60% of the vote.
Mr Corbyn, who began the contest as an outsider, saw off a challenge from Andy Burnham, Yvette Cooper and Liz Kendall.
Tom Watson has been elected as the new deputy leader of the Labour Party.
The news was announced at a conference in central London.