Competence in neonatal pain management is influenced by the clinician’s knowledge, attitudes, and skills. The impact of an educational program on enhancing competence among Thai neonatal nurses and midwives has never been explored. This study aims to evaluate the impact of an educational program to increase nurses’ and midwives’ competence in neonatal pain management in Thai neonatal intensive and special care units (NI/SCUs). A web-based learning package with pre-, post-, and follow-up online questionnaire was administered to 68 neonatal nurses and midwives. There was a substantial increase in the total mean scores of knowledge, attitudes, and perceived self-competence in the post- and follow-up phases compared to the pre-test phase (p < 0.001). The educational program had a significant impact on Thai NI/SCU nurse and midwife competence regarding neonatal pain management. Ongoing education is needed to sustain clinicians’ competence in this area.