We investigated school nurses' experiences, perceived government support, school nurses' acceptance of responsibility for medication administration, perceived stress, and perceived competence of medication administration and analyzed factors associated with perceived competence. In this cross-sectional study, from February to April 2023, we conducted an online survey of 269 school nurses serving at K-12 schools in Taiwan. The results revealed that although 71% of the participants had prior experience with medication administration, they reported low competence and high stress in areas such as drug interactions, adverse drug effects, and referrals. The school nurses' disagreement with responsibilities for medication administration emerged as the only factor to be significantly associated with perceived medication administration competence, accounting for 22.8% of the variance. We recommend implementing continuing training programs to provide school nurses with up-to-date medication information. Additionally, the development of practice guidelines is suggested as a means of enhancing nurses' competence and reducing their stress levels for the administration of medications.