The regulator has published its findings into an assessment of White Hat Gaming, which is part of its ongoing compliance work, revealing the operator has agreed to a £1.3m ($1.8m) regulatory settlement.
This payment in lieu of a financial penalty will be directed towards delivering the National Strategy to Reduce Gambling Harms.
The firm has now agreed to improve its automated prevention of spending once limits are hit, increase its safer gambling interactions and provide more thorough checks on source of funds.
The failings occured on White Hat Gaming sites including www.grandivy,com, www.21casino.com and more.
Examples include a customer losing £70,000 in three months, another customer losing £50,000 in just six hours and a third customer losing £85,000 in just over one hour.
Richard Watson, Gambling Commission executive director, said: “Through our compliance and enforcement activity we will continue our work to raise standards in the industry and continue to hold failing operators to account.”
Be sure to watch our problem gambling series for more on responsible gambling and how firms can improve their interactions with customers.