Net profit in the July to September period stood at 39 million euros (34.58 million pounds), up from 33 million euros in the same period last year, OPAP said. The figure was in line with analysts' forecasts.
Last year's third-quarter net profit was downwardly revised to exclude a one-off gain.
OPAP, which was sold by the state in 2013, launched a new business for video lottery terminals last year, which is expected to be a key growth driver in coming years.
Gross gaming revenue rose 3 percent to 368.9 million euros, with a growing contribution from the machines more than offsetting weakness in established games.
The company said it operated about 16,000 video lottery terminals in September and plans to add another 3,000 by the end of the year.
(Reporting by Angeliki Koutantou; Editing by Jan Harvey)