Having become the first female referee to be centrally contracted by the Rugby Football Union in 2016, she last year became the first female assistant referee in English rugby’s top tier.
Cox will break new ground this weekend when she becomes the first woman to take charge of a Gallagher Premiership league game.
The PA news agency understands she will officiate at Premiership champions Harlequins’ first home game of the season against Worcester at the Twickenham Stoop on Saturday.
Premiership Rugby posted on Twitter: “Huge congratulations to @SaraCoxRef.
“She’ll become the first woman to referee a #GallagherPrem league game on Saturday. Continually making history.”