Dan Jarvis has won the nomination to be the Labour candidate for Sheffield City Region mayor.
The MP for Barnsley Central won 58% of the vote in the contest against Sheffield Labour Councillor Ben Curran.
Jarvis had said he wanted to remain in parliament if he won the mayoralty.
But Labour’s National Executive Committee (NEC) decided on Tuesday that he could not do both jobs at once.
When he announced his intention to run for the mayor job, Jarvis said quitting parliament would be “needlessly squandering” his ability to put pressure on the government on behalf of the region.
In a statement following today’s result, Jarvis said the election came at a “pivotal moment for the Sheffield City Region”.
“To make the most of new opportunities, our first mayor will need to work with both local and national government to negotiate the best possible deal for the people of South Yorkshire,” he said.
“Only then will the mayor be able to end the status quo of how decisions are made and how public services are delivered; and use both devolution and cooperative principles to offer a more radical and effective way of serving the public.
“Today’s result is a vote of confidence in the platform on which I am standing, and the potential of devolution: first in the Sheffield City Region and then across ‘wider Yorkshire’.”
The post of the Sheffield City Region Mayor has been mired in controversy because, unlike similar rolls in Manchester and the West Midlands, no devolution and funding deal has yet been agreed to go with the appointment.
Two of the four South Yorkshire councils – Doncaster and Barnsley – have rejected a devolution solution centred on the county in favour of joining a pan-Yorkshire proposal.
Earlier this month, 18 of the 20 local authorities in Yorkshire agreed to back a proposal to the Government to deliver a One Yorkshire devolution deal. Sheffield and Rotherham were the only Yorkshire councils not to sign up to the plan.