Offline Betting in Person: At tribal sites only.Minimum Sports Betting Age in Washington: 18.Legal Sports Betting: Yes at tribal locations only.The current Washington sports betting market in the state is outlined below. Washington legalized sports betting at Tribal casinos in 2021, online sportsbooks are also legal in the state but so far only one sports betting app has been launched. Washington State Sports Betting at a Glance Is sports betting legal in Washington state?