Betfair, founded 10 years ago by one-time professional gambler Andrew Black and former JP Morgan trader Edward Wray, said underlying earnings before interest, tax, depreciation and amortisation rose 36 per cent to £42.4m in the six months to October.
That was ahead of an average forecast of £37.4m based on a poll of 10 analysts supplied by the company.
Betfair generated core revenue growth of 12 per cent year-on-year in the second quarter, and it has risen 13 per cent so far in the third quarter. Group revenue rose one per cent to £191.3m in the first-half.
"These results were driven by an excellent exchange performance following a very positive start to the football season and improved monetisation of activity," said departing chief executive David Yu in a trading statement on Wednesday.
The group added in a separate statement that it has appointed Chief Financial Officer Stephen Morana as interim chief executive.
Yu is stepping down at the end of the month with former Paddy Power Chief Operating Officer Breon Corcoran already named as his permanent replacement starting in August.