After university, she began her career in education and social policy, living in London and then Birmingham in the 1980s. During her time living in Birmingham, she taught the English language to refugees.[8][9] In 1992, she returned to live in Otley.[9]
Following her selection as deputy leader of the Leeds Labour group in 2003, once the party regained control of Leeds in 2010, Blake served as the Deputy Leader of the Council for five years to 2015. She was the Executive Cabinet Member for Children & Families during this period, overseeing the city's Children's Services' Ofsted rating change from "inadequate" to "good overall".[4] She has been involved in a number of national legal campaigns, worked with education authorities in Yorkshire to raise school standards in the area, and worked on crises and issues with student grades and school placements throughout her career.[5]
After then-leader Keith Wakefield stepped down, Blake was elected as the first woman leader of Leeds City Council in May 2015.[3] She chaired the Council's Executive Board, having also served on the boards for NHS Leeds and the West Yorkshire Police Authority. In April 2019, Blake was appointed to the board of Northern Ballet.[15] During her time as leader she was a key proponent of a public art project to celebrate the women of Leeds, which culminated in the unveiling of Ribbons by Pippa Hale in 2024..[16]
In December 2020, it was announced Blake would be conferred a Life Peerage after a nomination by Labour Party Leader Keir Starmer.[19] In February 2021, she was created Baroness Blake of Leeds, of Gledhow in the City of Leeds.[20]
Blake joined the opposition front bench in May 2021, as a Shadow Spokesperson for Housing, Communities and Local Government and an Opposition Whip.[21][2] In December 2021 she became Shadow Spokesperson for Business, Energy and Industrial Strategy and International Trade, and in February 2023 she became Shadow Spokesperson for Energy and Net Zero and Shadow Spokesperson for Business and Trade.[2]
On 11 July 2024, she became a Baroness-In-Waiting (Government Whip) in the House of Lords.[2]