Flutter announced a year-on-year revenue increase of 14% for 2019, up to £2.14bn ($2.75bn), in its preliminary results ending 31 December.
Meanwhile, Stars Group, which Flutter announced last October it has reached a deal to acquire, posted total revenue of $2.53bn for 2019, a significant yearly rise of 25%.
This would have given the merged organisation a combined 2019 revenue of $5.28bn.
However, Flutter's pre-tax reported profits dropped 38% to £136m, while underlying EBITDA decreased 15% to £385m.
The operator put down its rise in revenue to a strong standing in the US, where its FanDuel brand finished 2019 as the largest online sportsbook and casino.
For Stars Group, operating income showed a small increase of 2% up to £264.2m for the full year. Adjusted EBITDA increased by 18% to £921.1m.
Flutter CEO Peter Jackson said: "2019 was a very significant year for Flutter, with further successful expansion in the US, enhancement of responsible gambling initiatives within our business and the announcement in October of our proposed merger with Stars Group."
Stars Group CEO Rafi Ashkenazi said: "We not only began to see the full-year benefits of our transformative 2018 acquisitions, but executed on delivering a landmark media partnership in the US, with the launch of Fox Bet strengthening our position in this emerging market.”
