This study examined the association between grip strength and emotional working memory in middle-aged adults. Seventy-six males aged 40–60 years (mean = 48.5 years, SD = 5.4) participated in this cross-sectional study. They completed a muscular fitness assessment using a maximum grip strength test and emotional n-back tasks under two emotion conditions (fearful and neutral facial pictures) and two working memory loads (1-back and 2-back tasks). Hierarchical regression analyses indicated that greater muscular fitness was associated with superior working memory performance in the fearful condition in both the 1-back and 2-back tasks, after controlling for confounders. Greater muscular fitness was also associated with superior working memory performance in the neutral condition when the working memory load was high (2-back task) but not low (1-back task). These findings suggest a positive association between muscular fitness and emotional working memory and highlight the importance of maintaining muscular fitness for physical and cognitive-emotional well-being in middle-aged adults.