Former Belfast mayor Gavin Robinson beat outgoing MP Naomi Long in a contest that saw the vote of both parties soar on 2010.
Mrs Long won the seat in sensational fashion five years ago by defeating DUP leader Peter Robinson.
The DUP had been intent on regaining it ever since and, helped by an electoral pact with the Ulster Unionists, delivered the much-craved win by a majority of over 2,500.
“I am delighted the last five long years are over,” said the winning candidate, Mr Robinson.
“I am delighted a new day has dawned in East Belfast.”
He said voters had backed “someone they could trust”.
Mr Robinson said: “This has been an interesting election, it has been a polarising election, it is an election that has energised people right across the constituency and you can see that in the votes.
“People have been motivated to come out in increasing numbers in East Belfast. I think that has been good for democracy.”
He said the constituency had picked a party strong on the Union rather than the agnostic position offered by Alliance.
Mr Robinson polled 19,575 votes to Mrs Long’s 16,978. In distant third were the Conservatives with 1,121.
Mrs Long pointed out that her vote had gone up by around 4,000 on 2010.
She said her party’s campaign was “unrivalled” in the history of Northern Ireland politics
“We polled the best vote Alliance has ever polled,” she said.
“I want to say a huge thank you to the constituents who have backed me, to those who came out and voted in unprecedented numbers to support the vision Alliance put to them - a positive vision for Northern Ireland and its future, not a negative one.”