Armitage made her county debut in 2013, for Yorkshire against Surrey, scoring 25 runs and taking 3/2 from 1.4 overs in a 12-run victory.[3] In 2016, she was Yorkshire's leading run-scorer in the County Championship, with 153 runs including two half-centuries, as well as taking 7 wickets at an average of 12.85.[4][5] She was again Yorkshire's leading run-scorer in the 2017 Women's County Championship, with 192 runs, including 3 half-centuries.[6] Armitage began captaining Yorkshire in 2016, and captained her first full season in 2019.[7][8] In 2019, she scored 165 runs in the County Championship, the most for her side.[9] In 2021, she was the side's leading run-scorer and leading wicket-taker in the Twenty20 Cup, with 184 runs and 5 wickets.[10][11] She was again her side's leading run-scorer in the 2022 Women's Twenty20 Cup, with 214 runs including two half-centuries.[12]
In November 2019, Armitage was signed by Sydney Sixers for the remainder of the 2019–20 Women's Big Bash League season as a replacement for the injured Ellyse Perry.[14] She played five matches for the side, scoring 54 runs at an average of 10.80.[2] Later that season, she played six matches for Tasmania in the WNCL, scoring 103 runs at an average of 17.16.[15]
In 2020 she joined Northern Diamonds, and was named as captain of the side.[16] She led the side to the final of the Rachael Heyhoe Flint Trophy in their first season, and was the side's second-highest run-scorer, with 176 runs.[17] In 2021, she led the side to the finals of both the Rachael Heyhoe Flint Trophy and the Charlotte Edwards Cup, and was the side's leading run-scorer in the latter tournament.[18][19][20] She also played for Northern Superchargers in The Hundred, appearing in three matches.[21] In 2022, she led Northern Diamonds to their first title, winning the Rachael Heyhoe Flint Trophy.[22] She also scored her maiden century, and the highest score across the entire 2022 Rachael Heyhoe Flint Trophy, against Western Storm, scoring 131*.[23] She was also her side's leading run-scorer in the Charlotte Edwards Cup, with 151 runs.[24] She was also ever-present for Northern Superchargers in The Hundred, scoring 119 runs and taking one wicket.[25]