Smiling, a surprisingly common facial expression observed during the experience of acute pain, plays a pivotal role in shaping physiological and psychological responses. This study explores the influence of smiling on objective (i.e., heart rate) and subjective pain responses (i.e., pain reports and state affect) during a painful cold temperature task (N = 57, M(age) = 20.80, SD = 1.50). Our findings reveal that participants who spontaneously smiled during the task demonstrated not only lower heart rates but also reported higher levels of positive affect throughout the study. This research highlights the capacity of smiling to effectively mitigate both physiological and psychological responses to pain. By shedding light on the significance of this facial expression, our study offers valuable insights into ways in which smiling contributes to the promotion of positive physiological and psychological outcomes within the challenging context of pain.