The adverts appeared on the Looney Tunes World of Mayhem app in February, a game based on the Warner Brothers cartoons.
The app provided players with the opportunity to earn in-game gems by viewing adverts or performing tasks.
The adverts in question were found to be in breach of the Committees of Advertising Practice (CAP) Code, section 16.3.13.
This section states marketing communications for gambling must not be directed at those aged under 18, through the selection of media or context in which they appeared.
LottoGo, Dunder and Betfair said their adverts were placed by affiliate Tapjoy, and have since terminated contracts with it.
William Hill said it has blacklisted the app and would not advertise in it through Tapjoy or any other affiliate.
The app itself also had to accept blame for the complaints caused as it had been marked to display "mature-gambling" marketing. This was reportedly done in error and has since been corrected.
