To combat climate change, it is of vital importance that people change their behaviors. This study explores how influencers, or so-called greenfluencers, on Instagram could be utilized to stimulate pro-environmental behavior. We examine the effects of influencer-message congruence on influencer credibility (i.e. trustworthiness and expertise) and pro-environmental intentions, and compare the effects of influencer-message congruence between micro- (1000–10,000 followers) and meso- (10,000–1 million followers) influencers. Results of a 2 (influencer-message: incongruence vs. congruence) � 2 (influencer type: micro- vs. meso-influencer) online experiment amongst 201 Instagram users revealed that influencer-message congruence increased influencer credibility and pro-environmental intentions. Influencer credibility did not appear to be the underlying mechanism of the effect of congruence on pro-environmental intentions. Moreover, influencer type did not moderate the effect of influencer-message congruence. Our results imply that choosing an influencer whose image aligns with the pro-environmental message is important to stimulate Instagram users’ pro-environmental behavior.