The present study was the first (to our knowledge) to experimentally manipulate pro-environmental behaviour in order to assess its causal effects on affect and meaning in life. Participants (N = 343) were randomly assigned to either 1) a group who chose and engaged in a pro-environmental behaviour from a provided list of options; or 2) a control group who found and photographed public art from a provided list of options. The analyses found that there were no significant differences between the pro-environmental group and the control group, and all pre-registered hypotheses were unsupported. Exploratory analyses revealed a within-participants effect, whereby both conditions produced a significant effect on positive and negative affect, as well as meaning in life when compared to participants' average over the last four weeks. However, given that all findings were exploratory, the results should be considered speculative and can serve as direction for future research.