The Conservatives have won the constituency of Gower - a seat Labour has held for more than 100 years.
Following two recounts, AM Byron Davies gained the seat with 15,862 votes - a majority of just 27.
Labour's Liz Evans received 15,835.
Political expert Richard Wyn Jones, from Cardiff University, told BBC Wales it was "a bitter blow" for Labour who had held the constituency for nearly 100 years. The win has taken the tally of Tory-held seats in Wales to 11.
"I'm absolutely delighted that the people of Gower have put their faith in me," Byron Davies said.
Meanwhile, Stephen Kinnock, the son of former Labour leader Neil, has become an MP after Labour held on to Aberavon.
Elsewhere, the party also held Neath, Llanelli and Swansea East.
Conservative Stephen Crabb retained his Preseli Pembrokeshire seat where he has been a MP since 2005.
Labour's Geraint Davies kept Swansea West and Plaid Cymru's Jonathan Edwards held Carmarthen East. Tory Simon Hart held Carmarthen West and South Pembrokeshire.