Adjusted EBITDA was also up 59% on a reported basis, to £342m, and 35% on a pro forma basis to £684m.
However, profit before tax fell a sharp 70% to £24m. The operator's share price was up 2% to £127.80 after its H1 report was published.
Flutter attributed its H1 performance to enhanced diversification following its merger with The Stars Group, though it referenced COVID-19 disruption, which affected the company's H1 profit.
Peter Jackson, Flutter CEO, said: "The first half of 2020 has been defined by the outbreak of the global COVID-19 pandemic.
"The group's first half financial performance exceeded expectations as we benefitted from geographic and product diversification. In the period prior to COVID-19-related disruption, our businesses performed well with strong customer growth and favourable sports results. In the period thereafter, the cancellation of sports and closure of our shops led to reduced sports revenues in the UK and Ireland.
"However, this was more than offset by an increase in the number of recreational customers playing our poker and gaming products globally, as people sought new forms of home entertainment. In Australia and the US, the continuation of horse racing meant that overall sports revenues grew in both regions."
