Evidence regarding the relationship between physical fitness and learning achievement among students with mild intellectual disabilities remains limited, particularly in Indonesian special education settings. This study examined the association between physical fitness and learning achievement among students with mild intellectual disabilities at SDLB Negeri 2 Padang, a public special elementary school in Indonesia. A quantitative cross-sectional correlational design was employed involving 21 second-grade students selected through saturated sampling. Physical fitness was assessed using the Level 2 Indonesian Student Fitness Test (TKSI), while learning achievement was measured using students’ official academic records. Data were analyzed using descriptive statistics and simple linear regression. The mean physical fitness score was 10.57 (SD = 3.37), while the mean learning achievement score was 77.07 (SD = 7.77). Regression analysis revealed a significant positive association between physical fitness and learning achievement (b = 2.228, SE = 0.135, β = 0.967, p < 0.001), with the model accounting for 93.5% of the variance in learning achievement (R² = 0.935). Students with higher physical fitness scores tended to demonstrate higher learning achievement within the observed sample. However, given the correlational design, small sample, and single-school setting, interpret the findings as preliminary evidence of association rather than causation. These findings provide context-specific evidence regarding the relevance of physical fitness assessment within adaptive physical education for students with mild intellectual disabilities.