Sport Wales' latest Active Adults survey showed 41% of adults are "hooked on sport" - take part three or more times a week - up from 39% in 2013 and 29% in 2008.
About 67% of those not already "hooked" would like to do more sport, the survey found.
More than 8,000 people aged 15 and over were interviewed as part of the study.
While the survey showed volunteers had fallen slightly from 10% of adults in 2012 to 9% in 2015, there had been a 25% increase in hours volunteered.
However, it found there are still gaps in participation between males (46%) and females (35%), disabled (29%) and non-disabled (48%).
The study also showed those from Wales' most deprived areas are less likely to be hooked, with 39% of people taking part in a sport.
Sport Wales chief executive Sarah Powell said: "What these results show is that we have been successful in sustaining the incredible swell in numbers of volunteers and participants which followed the London 2012 Olympics and Paralympics."
But she said they needed to "continue to evolve our approach" to make sure there was sport on offer for everyone's needs.
If you've been inspired to get involved in sport, you can see our full list of activity guides or try our Activity Finder to find events and activities near you.
More than one million people in Wales want to participate in more sport, a new survey has revealed.