Purpose: This study aimed to analyze the effects of workload and work-life balance on work motivation and teacher performance, the effect of work motivation on teacher performance, and the mediating role of work motivation in the relationships between workload, work-life balance, and teacher performance. Methods: This study employed an explanatory quantitative approach with a cross-sectional design. The population consisted of 48 active teachers at SMP Islam Athirah Bukit Baruga, all of whom were included using census sampling. Data were collected through a five-point Likert-scale questionnaire comprising 38 items representing 16 indicators. Validity, reliability, and descriptive statistics were assessed using SPSS, while the relationships among variables were tested using path analysis in AMOS 24 based on four composite scores. The mediating effects were examined using the Sobel test at a 5% significance level. Results: The results showed that workload had a positive and significant effect on work motivation (β = 0.189; p = 0.003), while work-life balance also had a positive and significant effect on work motivation (β = 0.217; p = 0.032). Workload had no significant direct effect on teacher performance (β = −0.051; p = 0.668), whereas work-life balance had a positive and significant effect on teacher performance (β = 0.298; p = 0.013). Work motivation had a positive and significant effect on teacher performance (β = 0.613; p < 0.001). Furthermore, work motivation significantly mediated the effect of workload on teacher performance (standardized indirect effect = 0.116; p = 0.014) and the effect of work-life balance on teacher performance (standardized indirect effect = 0.133; p = 0.049). The model explained 6.7% of the variance in work motivation and 38.6% of the variance in teacher performance. Thus, six hypotheses were supported, while H3 was not supported. Implications: The findings highlight the importance of strengthening teachers' work motivation, managing workload proportionally, and maintaining a healthy work-life balance to improve teacher performance. In practice, school management should develop workload allocation and employee-support strategies that foster teacher motivation while protecting work-life balance. Future studies may incorporate larger samples, longitudinal designs, and additional organizational or individual factors to provide a more comprehensive understanding of teacher performance.