Consumers in Arizona spent a total of $461.5m (£385.1m/€452.6m) on sports betting during May, while gross revenue for the month amounted to $55.2m.
Of this total handle, $456.7m was bet online, while just $4.6m was spent wagering at retail sportsbooks across Arizona.
Players won $405.3m during the month, which left $55.2m in revenue, up 48.4% month-on-month from $37.2m in April.
After including $13.8m in free bets and promotional credits, taxable revenue for the month was $41.4m, a 151.5% improvement from $16.5m in the previous month.
FanDuel claimed top spot in terms of handle, processing a total of $152.4m in wagers, split $148.7m online and $3.6m for retail wagering. DraftKings placed second with $141.1m in online bets, then BetMGM with $84.2m worth of online wagers.
Turning to gross revenue and FanDuel also led the way with $24.8m in combined online and retail revenue, ahead of DraftKings with $14.3m in online revenue and BetMGM on $10.0m.