(1) Purpose: Conflicting information exists regarding the relationship between obesity, leisure-time physical activity (PA), and disability in people with multiple sclerosis (PwMS). We aimed to investigate the association between leisure-time PA and weight status in a relatively large cohort of PwMS. Furthermore, we examined this relationship according to the level of neurological disability. (2) Methods: The study included 238 PwMS (138 women) with a mean Expanded Disability Status Scale (EDSS) score of 2.5 (standard deviation [SD] = 1.7), mean disease duration of 6.4 (SD = 8.2) years, and mean age of 40.5 (SD = 12.9) years. Obesity was defined using two different metrics, each based on body mass index (BMI). Leisure-time PA was determined by the Godin–Shephard leisure-time PA questionnaire. Statistical analyses included multivariate logistic regression, the chi-square test, and Pearson coefficient correlations. (3) Results: The unadjusted odds ratio (OR) between leisure-time PA and BMI based on the World Health Organization’s (WHO) definition was 1.070 (p = 0.844) for overweight and 1.648 (p = 0.254) for obesity. The adjusted OR was 1.126 (p = 0.763) for overweight and 1.093 (p = 0.847) for obesity after adjustment for age, gender, and disability status. Chi-square analysis revealed no significant correlation between leisure-time PA and obesity (p = 0.564) according to the BMI threshold for PwMS. The unadjusted OR (95% confidence interval [CI]) between disability level and BMI based on the WHO definition was 1.674 (p = 0.220) for overweight and 0.618 (p = 0.460) for obesity. The adjusted OR was 1.130 (p = 0.787) for overweight and 0.447 (p = 0.234) for obesity after adjustment for age, gender, and leisure-time PA. Similarly, chi-square analysis revealed no significant correlation between disability level and obesity (p = 0.701) per the BMI threshold for PwMS. (4) Conclusions: No association was found between leisure-time PA and BMI in PwMS. An additional finding was the absence of any association between obesity and neurological disability level in the multiple sclerosis cohort.