Friday night's WNBA matchup between the Indiana Fever and Washington Mystics averaged a 0.6 rating with 1.02 million viewers on ION.
The viewership represented the most-watched game ever on the channel. The previous high for the channel was a game between the Fever and Sparks earlier this season, which averaged 724,000 viewers.
It was also the sixth WNBA game this season to cross the million viewer threshold.
The league previously went 16 years without a seven-figure audience.
The Fever have set record viewership numbers on ION, NBA TV, ESPN, ESPN2 and ABC this season.