Background: The need for client feedback in assessing healthcare services is widely recognized. However, little is known about the satisfaction of adolescent clients utilizing healthcare services in Malaysia. To the best of our knowledge, there is no validated instrument to measure the satisfaction of adolescent clients attending health clinics in Malaysia. This cross-sectional study aimed to determine the reliability of the Malay version of the Malaysian Ministry of Health’s Adolescent Client Satisfaction Questionnaire among adolescents attending health clinics in northeastern Malaysia. Methods: A cross-sectional study was conducted in January 2019 among adolescents aged 10–19 years attending four designated health clinics in the northeastern state of Peninsular Malaysia. The test for Cronbach’s α was performed to determine the internal consistency reliability. Results: There were a total of 85 adolescent clients involved in this study. The mean age of respondents was 15.6 years. The majority of respondents were female, Malay, students, and had attained a secondary level of education. The mean total satisfaction score was 78.35. The internal consistency reliability according to the Cronbach’s α of the domain was 0.854, which is considered highly reliable. The corrected item-total correlation for the domain was acceptable as it was ≥0.4. Conclusion The Malay version of the Malaysian Ministry of Health’s Adolescent Client Satisfaction Questionnaire has excellent internal consistency reliability. Therefore, it may be recommended as a tool to measure the satisfaction level among adolescents attending health clinics in Malaysia.