The Commission collated the figures from some of its largest licensees, representing around 80% of the total British online market.
Gross gambling yield from those operators totalled £496.1m, down from £533.4m in May.
Real event betting accounted for close to half of the total GGY, at £242.2m, a slight increase from £238.8m in May as June was the start of Euro 2020. Slots was the next largest vertical, bringing in £180.7m, but this was down significantly month-over-month from £211.2m.
Other casino games brought in £59.0m, down 9.6%, while virtual betting brought in £5.9m, down 18.0%.
Esports betting brought in £1.0m, down 49.7% from May 2021, and 78.2% behind its £4.6m peak in May 2020.
GGY for poker was down 19.8% at £5.9m, while other verticals brought in £1.4m, compared to £1.7m in May.
By vertical, real event betting continued to account for the largest number of active players during the month, which saw an uptick of 9.1% from May, to 5.6 million.
The number of slots players increased 1.1%, to 3.1m, while other gaming including casino saw an increase in active players of 1.5% to 2.2m.
The number of active players in virtual betting was down 8.1%, to 216,794, while the number of poker players decreased from 282,175 to 257,065.
While the number of active slots players increased, the number of bets placed on slots was down 9.6% to 5.57bn.
The number of bets placed on all other verticals also decreased, with real event bets down 9.1% to 272.6m, bets on other gaming including casino down 8.0% to 267.5m, bets on poker down 15.1% to 73.5m, and virtual bets down 13.0% to 13.4m.
A decrease in the number of bets placed was reflected in the average gaming session length recorded, which stood at 19 minutes compared to 21 minutes in May. The total number of sessions lasting over an hour also decreased by 9.3%, to 2.3m.