There are celebrations in the Conservatives camp with gains in target seats Cardiff North, Aberconwy and the Vale of Glamorgan.
They have also gained Montgomeryshire from the Lib Dems, unseating Lembit Opik, arguably one of Westminster's most colourful characters.
In another surprise, the party also gained Carmarthen West and Pembrokeshire South from Labour.
The Conservatives have eight seats in Wales, up from three in 2005.
Jonathan Evans beat Labour's Julie Morgan, wife of the former First Minister Rhodri Morgan, to win the top Tory target seat of Cardiff North by just 194 votes.
Mr Evans thanked Mrs Morgan for what he called her 'selfless service' to her constituents.
He said: "May I pay tribute to Julie Morgan your outgoing Member of Parliament.
"That's not a new statement for me. At our last hustings I paid tribute to her, perhaps unusually for a political rival."
Speaking of the campaign, he said: "It has been an enormously difficult task for the Conservatives in managing to wrest this seat from the Labour party, as we have seen from the margin of victory.
"We have seen Gordon Brown here. We have seen all of the shadow cabinet - as they will be - here, and we have been dealing with an enormously popular constituency MP and yet we have prevailed."
Speaking to BBC Wales after his election in Montgomeryshire, Glyn Davies said: "It's something of a shock, really.
"But it's a great result for me, and a great result for the team that's been working for me, and we are pretty thrilled about it."
"He said that over the last three years he and his campaign team had concentrated not on winning the election but on improving public services in the area, and that this emphasis, plus his eight years as an assembly member had satisfied the constituents.
Guto Bebb had a 3,398 majority in Aberconwy over Labour - a new seat created after boundary changes.
"We have actually worked extremely hard. We have fought every single council seat that's been going over the last six or seven years and I think we have convinced the people of this seat that we are serious about representing this constituency."
He added that the Conservatives were making "very significant gains in Wales."
Asked about the possibility of cooperating with other parties in the event of a hung parliament, he said: "We have a duty if there is a hung parliament to see if a form of government can be put together which will serve the interests of the people of this country."
In the Vale of Glamorgan, Tory Alun Cairns, also an AM, becomes the new MP.
After the declaration, he said: "I thought it was going to be much tighter. It's a classic two horse race. There's a long history of Conservatism here and it's taken a while to get it back.
"I'm very surprised at the size of the majority. It's been a very positive campaign."
David Jones, the re-elected Conservative MP for Clwyd West, told BBC Wales: "The Conservative Party is making gains - and substantial gains, and bearing in mind that we were attacking the government from a very low base, I think we are doing pretty well.
"It looks as if the Conservative Party is going to be the largest party in this parliament and therefore it has the moral authority to form the next government."
The Conservatives also retained Preseli Pembrokeshire and Monmouth, and took Carmarthen West and Pembrokeshire South from Labour.
The new MP Simon Hart said: "I am very very happy with the outcome."
Speaking about his defeated Labour opponent, the former sitting MP Nick Ainger, Mr Hart said: "I never mind saying that I had no axe to grind with Nick and I never have done. All political cycles come to an end.
"We've had our differences, but I respect him enormously and I very much hope to be able to offer the commitment to the constituency that he has."