With the three new additions, the Responsible Gambling Coalition stands at nine members.
These are Bally's, BetMGM, DraftKings, Entain, Fanatics, FanDuel, Hard Rock Digital, PointsBet and MGM Resorts International.
Rachel Kasper, SVP of Legal and Compliance of PointsBet US, said: "PointsBet is proud to join the Responsible Gambling Coalition to continue bolstering our commitment to this important topic.
"Responsible gambling is a core priority for our business and requires meaningful collaboration with all stakeholders, inclusive of operators competing within the same markets, to promote this aspect of our industry and ensure safe practices are followed."
The operators have assembled the coalition to agree on industry-led responsible gaming standards and 12 main principles.
Anthony D'Angelo, Sr. Manager, Responsible Gaming for Fanatics Betting & Gaming, said: "We are proud to collaborate and partner with our industry colleagues.
"We are committed to the 12 responsible gaming principals and providing our fans tools and resources to enjoy our products."
Since its inception, the Responsible Gambling Coalition has appointed ambassadors, established partnerships with research institutions and problem gambling organisations, and received the RGCheck accreditation from the Responsible Gambling Council.
Danny Crook, SVP of Operations at Hard Rock Digital, said: "Hard Rock Digital is pleased to have this opportunity to collaborate with our fellow operators to promote and maintain an industry-wide atmosphere of responsible gambling.
"We're committed to serving our players with educational tools, resources, and support to ensure a safe and enjoyable online gaming experience."
The initial announcement on the 12-point pledge was released during the American Gaming Association’s Responsible Gaming Education Month.