Candidate Lovinyer Daley polled 783 votes in the ward to defeat Conservative Steve Hall, who gained 412 votes. Just 13.18 per cent of the electorate turned out at the ballot box.
She replaces disgraced former councillor Harman Banger, an ex-cabinet member who was convicted of fraud and forced to resign in December.
An emotional Ms Daley told supporters: “I can’t believe it. This literally means the world to me. I’ve waited for this moment for so long, to be able to represent the area that made me who I am.
“Lots of people said ‘you’ll never make it’, but here I am. Now I am really looking forward to helping people. That has been my aim all along, what I have been telling people on the doorstep, and that is definitely what I intend to do.
“I want to thank all of my friends, my agent Beverley, my best mate, my family, the Labour Party, colleagues and members.
“But I want to bring it back to why I’m here. I want to thank the people that voted for me. I wouldn’t be here without them, and I will do my best to fight for them for the next however many days I am now their councillor,” she added.
Councillor Beverley Momenabadi, who acted as Ms Daley’s agent and guided her on the campaign trail, said: “It’s no surprise to me that the people of East Park have come out today to vote Labour.
“People are going through the worst cost of living crisis of their lifetime at the moment; struggling to pay heating bills, struggling to pay electricity bills and using food banks.
“And this includes working families and individuals in East Park. They voted for a local candidate who knows the area, knows the people and grew up around there and brought her kids up there."
The result means Labour continues to dominate the council, holding 44 seats to the Conservatives 16.
Despite defeat in East Park, the Conservative vote share increased by 17 per cent in the ward.
The party is bidding to build on gains made in last year's local elections when voters in the city head to the polls on May 5.