Increasingly, unhealthy food is being advertised through online games known as advergames. The advergame is designed for entertaining fun to promote the brand featured in the game. But what happens if the food advertised is healthy or the source of the game is non‐commercial? This study examines how people's entertainment (flow experience) interacts with their inference about the persuasion impact of food brands featured in an advergame, which vary according to their persuasion knowledge about the source (e.g., non‐commercial versus commercial) and the perceived persuasion effect on self (e.g., beneficial versus harmful). Results of an experiment show that flow is positively associated with persuasion effects of the advergame. Brand attitudes and purchase intentions were the most favorable for non‐commercial brands with perceived benefits (healthy food) followed by commercial brands (healthy food) and commercial brands with harmful effects (less healthy food). However, persuasion effects for purchase intention were mitigated when participants were immersed in a flow state. Ramifications for persuasion and health promotions are discussed. Copyright © 2016 John Wiley & Sons, Ltd.