Jeremy Corbyn will shake up British politics and represents a reaction against the legacy of former Prime Minister Tony Blair, Labour leader Andrew Little says.
However, the leader of the New Zealand Labour Party is reserving judgment on whether Mr Corbyn can now push on and become prime minister.
The choice of Mr Corbyn, a backbench MP and antiwar campaigner, means the British Labour Party has one of the most left-wing leaders in its history.
Mr Little said the result would "really shake things up in UK politics".
"What he represents is a style of communicating about issues that is shorn of all the PR spin and stuff, and I think that's what people were looking for," Mr Little said.
"We will certainly be looking very keenly to see how he goes."
Mr Corbyn's election represents a shift to the left after the New Labour era of Tony Blair and Gordon Brown.
In the lead-up to the election, Mr Blair had urged party faithful against voting for Mr Corbyn, arguing the party was in the worst danger in its 100-year history, and faced possible annihilation if his advice was ignored.
"It is a bit rich for Tony Blair to say that ... it may well be that it is Tony Blair's legacy that there has been such a negative reaction to, which Jeremy Corbyn offers an alternative to," Mr Little said.
"There are plenty of people in the UK who have done it pretty tough under the austerity measures of the Cameron Government, and Corbyn has offered an alternative to that."
In the campaign, Mr Corbyn's key proposals were to apologise for Labour's role in the Iraq war, introduce quantitative easing to fund infrastructure, and the creation of a national education service.