Labour comfortably held their seat at Mitcham and Morden as Siobhain McDonagh was re-elected with 27,978 votes, a majority of 16,496.
Conservative candidate Toby Williams came a distant second place on 11,482 votes, with the Liberal Democrats’ Luke Taylor third on 3,717.
Jeremy Maddocks of the Brexit Party polled 1,202 votes, followed by the Green Party’s Pippa Maslin on 1,160, and Des Coke of the Christian Peoples Alliance last with 216 votes.
Ms McDonagh has recorded majorities in excess of 10,000 in every election since 1997.
She said: “It is my regret that as a national Labour Party we let many of our supporters down tonight.
“Brexit is coming and a recession not far behind it.
“It will be very hard for the most excluded and the poorest in our community and we, the Labour Party, did that by allowing Boris Johnson and his MPs to win when they were so beatable.
“But not by us in our current state, I hope that over the next year the Labour Party will come to its senses.”
Runner up Mr Williams said: “It’s very encouraging to see the Conservative vote increase and the Labour majority significantly reduce.
“We could feel a number of Labour votes coming over to us during the campaign and I think this result shows that came to fruition at the ballot box.
“I would love to stand again, I have thoroughly enjoyed standing here. I think this is a great part of London – who knows where I will be in four or five years time. “