40 per cent of bets placed with major bookmakers are via phones and tablets.
New data from Juniper says smartphone and tablet-based gambling on sports will reach $45 billion by 2017. It's a huge rise on the $13bn generated last year, when $3 billion of the total was powered by the UK.
And it's being powered by the changing habits of consumers, who are actively moving their activity to mobile channels.
Dr Windsor Holden, report author, Juniper Research, said: "Companies such as Ladbrokes, William Hill and Paddy Power are all seeing 40 per cent or more of online sportsbook customers placing bets via a mobile or a tablet, with the result that those devices already account for around 20 per cent of bets placed."
Companies are now moving towards browser-based apps, though native formats are seen as the best way for their services to be found.
Additionally, gambling of all types via mobile is set to reach $100 billlion by 2017.