Conservative Penny Mordaunt swept to victory in Portsmouth North, taking 44 per cent of the vote.
The Tory ousted Labour's Sarah McCarthy-Fry, beating her by more than 7,000 votes.
It is the first time the constituency has voted for a Conservative candidate since 1992.
The vote saw a six per cent swing to the Tories.
Miss Mordaunt, who had stood for election in Portsmouth North in 2005, said: 'We did it.
'I'm so pleased so many people came out today, including many who have never voted before.
'I will have a quick tipple today then the real work starts on Monday.'
Miss Mordaunt, who described herself as 'tired and emotional' after a seven-hour count, pledged to bring money to her constituency.
She said: 'The country faces a crisis, but people voted for optimism and hope.
'It is a challenge to which I will rise.
'We can definitely bring jobs and greater investment to this deprived constituency.
'We must address the problems people in Portsmouth North are facing immediately.' Mrs McCarthy-Fry, who was defending a small majority at the election, was visibly upset when she spoke to The News immediately after the result.
But she said: 'This is my city, I live here and my family live here, I will not desert it, I will continue to work hard for it.
'We will hold the Conservative party to account and make sure that Portsmouth North is not ignored as the new government, whatever shape it takes, continues the recovery.'
She added: 'Penny faces a huge challenge – she will find it the most difficult job she has ever done, but it is a very rewarding one.'
Liberal Democrat Darren Sanders came third in a disappointing night for his party.
He said: 'I wish Penny good luck and I hope we can all work well together in hard times that face the country so we can come through this crisis with faith and hope.
'Sarah and I will be around and I know that we will both offer every assistance we can to Penny and Portsmouth North.'
Penny Mordaunt, Con, 19,533
Sarah McCarthy-Fry, Lab, 12,244
Darren Sanders, Lib Dem, 8,879
Mike Fitzgerald, UKIP, 1,812
David Knight, ED, 1,040
Iain Maclennan, Gr, 461
Mick Tosh, (TUSC), 154