Stephen Doughty admitted a turnout of 25.35% was 'disappointing', but he thought the increase in Labour's share of the vote since 2010 was 'remarkable'.
He told our Political Reporter Owain Phillips that his resounding victory 'shows that people are fed up of the policies of this coalition government and they want to see a different way ahead.'
Stephen Doughty will be the new MP. He's increased Labour's majority slightly, but turnout was just 25%.
Counting begins to find out who voters in Wales' biggest constituency by population have chosen as their new MP.
It's the final day of campaigning before the Cardiff South and Penarth by-election.