The association between host country language proficiency and disease prevention among migrants is underexplored. The objective of this study is to assess the extent to which self-reported command of the Thai language is associated with adherence to COVID-19 protective behaviors (CPB) among Myanmar migrant workers in Thailand. We distributed a self-administered structured questionnaire in Burmese language to 1,050 Myanmar migrant workers in Southern Thailand from September 2022 to January 2023. The questionnaire included background characteristics, self-reported Thai language proficiency based on the Common European Framework Reference (CEFR), and self-reported CPB adherence at residence and workplace. We analyzed data using descriptive statistics and multivariate linear regression analysis. Although slightly less than half of the participants reported CEFR A1 level or higher in Thai speaking and listening skills, less than 10 percent did so for reading and writing skills. Workplace COVID-19 preventive adherence scores were initially found to be significantly associated with A1 level or higher speaking and listening skills. However, after adjusting for confounders, these associations were not statistically significant (Speaking skill's Adjusted Beta = 0.713, 95% CI = -0.011, 1.437; Listening skill's Adjusted Beta = -0.367, 95% CI = -1.087, 0.353). No significant associations were found between any language skill domain and residence COVID-19 preventive adherence scores for both unadjusted and adjusted analysis. The study findings may have implications for relevant stakeholders in migrant services, migrant health, and infectious disease control. However, information biases, language barriers, and lack of generalizability should be considered as caveats in the interpretation of the study findings.