Lack of health care worker (HCW) training is a barrier to implementing youth-friendly services. We examined training coverage and self-reported competence, defined as knowledge, abilities, and attitudes, of HCWs caring for adolescents living with HIV (ALWH) in Kenya. Surveys were conducted with 24 managers and 142 HCWs. Competence measures were guided by expert input and Kalamazoo II Consensus items. Health care workers had a median of 3 (interquartile range [IQR]: 1-6) years of experience working with ALWH, and 40.1% reported exposure to any ALWH training. Median overall competence was 78.1% (IQR: 68.8-84.4). In multivariable linear regression analyses, more years caring for ALWH and any prior training in adolescent HIV care were associated with significantly higher self-rated competence. Training coverage for adolescent HIV care remains suboptimal. Targeting HCWs with less work experience and training exposure may be a useful and efficient approach to improve quality of youth-friendly HIV services.