Variables of connectedness (pro-socialness and connectedness to nature) are related to sustainable behavior and attitude. This study investigates if athletes of different types of sport differ in their sustainable attitudes and behavior. Two-hundred twenty-five athletes participated, 53 from individual indoor sports, 46 from individual outdoor sports, 65 from team indoor sports, and 61 from team outdoor sports. All athletes completed questionnaires on pro-socialness, connectedness to nature, and sustainable attitudes and behavior. The results provide evidence for the relationship between connectedness and sustainable attitudes and behavior. Sustainable attitudes were predicted by connectedness to nature (β = 0.287, p < 0.001) and age (β = 0.230, p = 0.048), sustainable behavior by connectedness to nature, (β = 0.250, p = 0.001) and pro-socialness (β = 0.268, p = 0.003). There is no difference in pro-socialness in athletes from individual vs team sports. However, athletes practicing outdoor sports are more connected to nature than those practicing indoor sports. Moreover, athletes from individual outdoor sports show the highest values in sustainable attitude and behavior. The underlying mechanism for this result might be worth to be investigated in more depth.