He is currently shadow business secretary and has been MP for the constituency since 2010.
On Thursday, he was re-elected with 53 per cent of the votes.
Today Umunna said: “I will be standing for the leadership of the party. I think we can and should be winning in seats like Swindon; north, south, west and east – we can absolutely win as a party.”
He is the second candidate to declare in the race to takeover from Ed Miliband as Labour leader: Liz Kendall, MP for Leicester West, has also announced she will be standing.