The negative impact of Internet use on adolescents has received much popular attention and has also become a popular research topic. How to induce adolescent players to change their attitudes toward online gaming is one of the most important issues in online gaming addiction. The present study is based on the less-leads-to-more effect of dissonance theory. Experimental research was conducted to examine the effects of rewards and decision freedom on attitude change toward online gaming among adolescents considered at risk for addiction. The results supported predictions based on external justification in dissonance theory. Specifically, fewer rewards produced greater attitude change toward online gaming in the condition of personal freedom of choice after participants exhibited attitude-discrepant behavior. However, the less-leads-to-more effect was not prominent in the condition without personal freedom of choice. Adopting a reward strategy to induce game players to disengage online gaming is discussed.