It marked a 71% increase over last year's audience at a critical time for the women's sport, after FIFA said late last month it had rejected a number of bids for the 2023 Women's World Cup broadcast rights for being too low.
The quadrennial tournament is less than nine months away.
The championship broadcast was also seen as a crucial moment for the top-flight American league grappling with the fallout of a damning abuse and misconduct inquiry in its 10th season.
The match was played in primetime on network television during Game 2 of the World Series, a year after fans and players were left outraged when the championship match was relegated to a 12 noon ET time slot, also on the CBS network.
League MVP Sophia Smith (22) opened the scoring in the 2-0 win for the Thorns, who also lifted the Challenge Cup last year.
