Davies resurrected the hit BBC sci-fi show in 2005 but waved goodbye to the Tardis four years later.
He is now heading back to take over from Chris Chibnall, after it was confirmed earlier this year that both he and current Time Lord Jodie Whittaker were leaving.
Davies will be back in 2023, the year the show marks its 60th anniversary.
🚨 BREAKING NEWS 🚨
Russell T Davies to return as Doctor Who Showrunner to celebrate the 60th anniversary in 2023, and series beyond. BBC Studios are partnering with Bad Wolf to produce.
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— Doctor Who (@bbcdoctorwho) September 24, 2021
“I’m beyond excited to be back on my favourite show,” he said on the Doctor Who website.
“But we’re time-travelling too fast, there’s a whole series of Jodie Whittaker’s brilliant Doctor for me to enjoy, with my friend and hero Chris Chibnall at the helm – I’m still a viewer for now.”
Chibnall said it was “monumentally exciting and fitting that Doctor Who’s 60th anniversary will see one of Britain’s screenwriting diamonds return home”.
“Russell built the baton that is about to be handed back to him - Doctor Who, the BBC, the screen industry in Wales, and let’s be honest everyone in the whole world, have so many reasons to be Very Excited Indeed about what lies ahead,” he said.
Piers Wenger, BBC director of drama, said: “As the 13th Doctor prepares to embark on new and extraordinary adventures, the winds of change are blowing… bringing with them news to delight Doctor Who fans across the globe.
"We are thrilled that Russell is returning to Doctor Who to build on the huge achievements of Chris and Jodie. Thank you to the two of them and the team in Cardiff for all they continue to do for the show and hello Russell, it’s wonderful to have you back.”
Doctor Who first aired on the BBC in 1963 and always had a male Time Lord at the helm of the Tardis until Whittaker took over four years ago.
It was confirmed this year that she and Chibnall would bow out after another series and a set of specials.
Watch: Russell T Davies speaks about It's A Sin