Wallace has career-high WTA rankings of No. 243 in singles, achieved on 15 January 2018, and 326 in doubles, set in November 2017. She won six singles and two doubles titles on the ITF Circuit.
She was born and raised in Inverness, Scotland before moving to Melbourne, Australia when she was ten and representing Australia at international tournaments. After six years, Wallace and her family moved back to Scotland where she then chose to represent Great Britain. In 2015, Wallace made the decision to represent Australia again in international sporting competitions due to lack of support from the Lawn Tennis Association.
As a junior, Wallace had a career-high ranking of No. 37, achieved in January 2014. Her junior highlights include reaching the third round of the girls' singles at the Australian Open and the French Open in 2014.