Sue Redfern became the first on-field female umpire in the Vitality Blast as Gloucestershire beat Middlesex in Bristol on Sunday.
The 45-year-old joined the Professional Umpires Team, the ECB's group of elite officials, in 2022 and is eligible to stand in men's and women's professional matches.
"I am really excited and really pleased to be part of this day today," she said. "Obviously there are more male umpires than female umpires, but today shows there is visibility of female umpires.
"It is important that we try to encourage more females to try and take up what is a fantastic opportunity and could be a career for someone in the future. So more women playing, coaching and umpiring can only be a good thing."
Redfern became the first female umpire to officiate on-field in a Blast fixture as she stood along with Alex Wharf at Bristol's Seat Unique Stadium, where all-rounder Ollie Price led the way for the home side.
The 21-year-old top scored with 46 and shared in crucial partnerships of 60 with Miles Hammond and 52 with Zafar Gohar as Gloucestershire chased down a target of 140 with 10 balls to spare to register their second win in three days.
In April, New Zealander Kim Cotton became the first female on-field umpire to stand in a men's international between two full-member nations when she officiated in New Zealand's T20 against Sri Lanka in Dunedin.