The party’s candidate Councillor Stephen Morgan won the seat from incumbent Flick Drummond to turn the constituency red for the first time since the seat was created in 1918.
He said: ‘It feels absolutely fantastic to be the MP for the city. This is a historic moment for Portsmouth and I am really pleased to be one of this city’s MPs. Mrs Drummond had been the constituency’s MP for the last two years after winning it from the Liberal Democrats back in 2015.
She said: ‘Obviously I am very disappointed about it as there was a lot of things that I wanted to do as MP but I guess that is democracy.
‘Congrats to Stephen. I wish him well.’
She had previously stated that she ‘did not want’ the election but could see prime minister Theresa May’s thinking behind it.
Cllr Morgan was only elected as a councillor on Portsmouth City Council last summer for Charles Dickens ward.
He took the seat with 18,290 votes, beating Mrs Drummond in second with 16,736 and Liberal Democrat candidate Councillor Gerald Vernon-Jackson on 7,699 in third.