The DUP leader polled 11306 votes, while Ms Long topped the poll with 12,839 representing a massive 22.9% swing in support.
It was a stunning setback for Mr Robinson who had held the seat since 1979.
Speaking after his defeat Mr Robinson said he would have preferred not to stand in this election but would continue to carry out his work in the Assembly.
Mr Robinson said: "I will continue to carry out vital work...I will always do my best to get the best deal for the people of Northern Ireland."
Thanking the voters Ms Long said: "I went to the electorate with a track record of hard work with a passion for east Belfast that I have lived in my whole life and with a dedication to serve them in an open and transparent way and give them my best and to build a better future for everyone in east Belfast.
"If that is what has won it, I'm pleased about that."
Sammy Wilson blamed the media for Mr Robinson's defeat.
"As far as the result for Peter is concerned it has to be seen in the context of a barrage against him by the media over the last six to nine months," he said.
"At the same time people have to recognise that despite all of those pressures he guided Northern Ireland to the completion of devolution, he has ensured that the Assembly has continued to function and improve it's work."
Ian Paisley Jnr claimed Peter Robinson had been the victim of a 'hunt him down' campaign.
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