Mr Miles’ candidacy follows news that a majority of Welsh Labour Senedd members have already pledged their support for the current education minister.
In a statement, Jeremy Miles said: “If I think back to when I was growing up, wondering about my place in the world as a young gay man from a working class family in Pontarddulais, I would never have imagined that one day I would be putting myself forward to lead our great party and our nation.
“In recent days, party members, from all parts of Wales, Cabinet and Senedd colleagues, MPs, councillors, peers, trade unionists, and many others in our movement have expressed their support for me to lead our party. I am hugely grateful.
“And so today I confirm I will be standing in the election to become Welsh Labour’s next leader, and to be First Minister of Wales.
“I am determined to build on Mark’s legacy and his unquestionable commitment to public service. As we look forward to the next quarter century in the journey of devolution, we must set our sights on an ambitious future for Wales, led by Welsh Labour.
“The Tories’ attacks on public services, austerity and their mismanagement of our economy, means things have been incredibly difficult for people across our country. We face many challenges ahead – but I am hopeful for the future.
“A Labour victory at the next general election is crucial for that more positive future. A UK Labour Government led by Keir Starmer, working with our Welsh Labour Government, can achieve so much more for Wales. Together, we will end the cycle of Tory crises that has worn down so many. We must do all we can to ensure a Labour win – we owe it to our country.
“And be in no doubt – a Welsh Labour Government which I lead, will always stand up for Wales.
“I will be setting out a bold, ambitious and exciting vision for Wales’ future. I hope you will join me in making that vision a reality. “
Mr Miles joins current economy minister, Vaughan Gething in the running for the Welsh Labour leader role.
