The former shadow equalities minister revealed she would run in the 2028 mayoral race if the current mayor decides not to seek a fourth term.
Ms Butler, who first entered Parliament in 2005, has already begun sharing videos highlighting issues across the capital, including in Notting Hill and Canary Wharf.
During an appearance on The Mirror’s web series Party Games, Ms Butler said: “London Mayor, to represent London.
“I’m a Londoner through and through, born in east London.
“Just having London the way I have experienced it and seen it and just making London wonderful for everyone and everyone being proud of London and being a Londoner.
“Yeah, I’d love to be a Mayor of London.”
When pressed on whether she would run in 2028, she said: “Once there’s a vacancy, I will pop my hat in the ring.”
Her comments come amid speculation over whether Sir Sadiq Khan, who recently won a historic third term, will stand again.
A City Hall spokesman said: “Sadiq hasn’t decided yet if he’s standing again at the next mayoral election.
“This is the same as the last election cycle when he didn’t announce his decision until much later in the mayoral term.”
Ms Butler is among several Labour figures tipped as potential candidates, alongside Tooting MP Rosena Allin-Khan, Walthamstow MP Stella Creasy, and Vauxhall MP Florence Eshalomi.
Labour is reportedly considering high-profile names such as actor Idris Elba and Dragon’s Den investor Deborah Meaden.
Speculation on the Conservative side includes ex-Olympian Sebastian Coe and former London minister Paul Scully.
Reform UK is believed to be weighing up Laila Cunningham as a candidate, despite earlier suggestions of former soldier Ant Middleton.
Recent Savanta polling puts Labour on 35 per cent, 12 points ahead of the Conservatives on 23 per cent.
The Liberal Democrats and Reform UK are tied at 14 per cent, with the Greens on 11 per cent.
Alternative polling from Find Out Now suggests Reform UK could reach 20 per cent, putting them in joint second with the Tories.