Garbett was first elected as a councillor for Hackney in Dalston ward in May 2022, receiving 1,446 votes with a turnout of 37.77%;[5] she was the first green councillor to be elected to the position. During the same elections she was the Green candidate for the directly elected executive Mayor of Hackney, coming in second place with 17% of the vote.[6]
On 10 February 2023 she was announced as the Green Party candidate for the 2024 London Mayor election.[7]
Following Hackney mayor Philip Glanville's suspension over a photograph taken with Cllr Tom Dewey, Garbett put forward a motion of no-confidence, but it did not reach a debate of the full council.[8] Mayor Glanville resigned two weeks later, vacating the position on 22 September 2023 and triggering a mayoral by-election.[9]
Shortly after she was announced as a candidate in the Mayoral by-election held on 9 November 2023,[10][11] questions were raised about her commitment to the campaign for City Hall, to which she answered: “I don’t think you could do both jobs, but I think you could run in both elections. Well - you could be the Mayor of Hackney whilst running to be the Mayor of London.”[12]
Garbett launched her manifesto on 8 April 2024.[13][14]