Having worked as an administrator with the NHS Business Services Authority, Welch became a football referee in 2010, but continued to work in her NHS post until becoming a full-time referee in 2019.[2][3][4] She had played football from a young age, and studied to be a referee with Durham County Football Association. Her first two matches were women's university games, followed by a Sunday League match in Sunderland, something she has described as being "a completely different kettle of fish" compared to the university games.[5]
Welch's appointment to referee the Harrogate v Port Vale match was announced by the Football Association on 30 March 2021.[9][11] The announcement made Welch the first woman to be appointed to referee an English Football League game, though not the first woman to referee during a game. Amy Fearn was substituted to referee the final 20 minutes of a match between Coventry City and Nottingham Forest in February 2010 when the original referee was taken off due to injury.[3][12]
On 29 December 2021, it was announced that Welch would be the first woman to officiate a third round men's FA Cup match. The game in question, between Birmingham City and Plymouth Argyle, was played on 8 January 2022.[13][14]
In November 2023, Welch was allegedly the subject of misogynistic chanting during a match between Birmingham City and Sheffield Wednesday; two 17 year olds were subsequently arrested.[21]
In August 2024, the PGMOL announced that Welch was to retire from officiating and that she would become their manager of the Select Group Women’s Professional Game.[29]