Cooper made her county debut in 2019, for Surrey against Warwickshire in the Women's Twenty20 Cup.[4] She went on to play four matches in the competition, taking four wickets including her Twenty20 best bowling figures, 3/22 taken against Wales.[5][6] In 2020, she took three-wicket hauls in two Women's London Championship matches.[7][8] In 2021, she took six wickets in the Twenty20 Cup and four wickets in the London Championship.[9][10] She took four wickets in the 2022 Women's Twenty20 Cup, including taking 2/6 from two overs against Sussex.[11][12] She took six wickets in the group stage of the 2023 Women's Twenty20 Cup, at an average of 11.00, including taking 3/12 from her four overs against Oxfordshire.[13][14]
Cooper was named in the South East Stars Academy squad for the 2021 season.[15] In a 100-ball match against Southern Vipers Academy, she took 3/5 from 20 balls.[16] She was promoted to the first team squad ahead of the 2022 season, but did not play a match for the side that year.[17] She was retained in the squad for the 2023 season, and made her debut for the side on 25 May 2023, against Sunrisers in the Charlotte Edwards Cup.[18][19] She played five matches overall for the side that season, all in the Charlotte Edwards Cup, taking four wickets at an average of 21.75.[20] She was also signed by Oval Invincibles for The Hundred, but did not play a match.[21] In 2024 she took 15 wickets in what would be her final season for Surrey.[22]
Cooper joined Yorkshire in 2025 and saw an instant increase in playing time. She took 34 wickets across all competitions, including a best of 3/22. Cooper was also part of the team that won the Metro Bank One Day Cup 2. In April 2026 it was announced she had signed a contract extension with Yorkshire through to the end of the 2027 season.[23]
Cooper will also return to the Hundred in 2026, having been drafted by Sunrisers Leeds.