This study aimed to assess the influence of taro mucilage (TM) and black seed oil (BSO) as an edible coating to extend guava fruits’ shelf-life and quality attributes. Four different edible coatings were applied, namely, T1 (1% TM + 0.75% glycerol + 0.5% BSO), T2 (5% TM + 0.75% glycerol + 0.5% BSO), T3 (0.75% glycerol + 0.5% BSO), and T4 (1% chitosan + 0.75% glycerol + 0.5% BSO). Different quality parameters, including weight loss, surface color, firmness, chlorophyll, vitamin C, phenolic content, antioxidant, malondialdehyde, and microbial load, were measured at a regular interval. Significant differences were observed between the coated and uncoated (control) fruits. Compared to the control fruit, weight loss was decreased in all the treated fruits, and T2 treatment retained the highest weight compared to other treatments. Fruits treated with T2 and T4 treatments retained high levels of vitamin C throughout the storage period. After 9 days, T4 treatment showed the lowest increase of microbial growth compared to other treatments. At the end of the storage period, results showed that the sample treated with 5% mucilage retained a higher level of polyphenol, antioxidant, and vitamin C content. Furthermore, the addition of BSO improved the antibacterial and antioxidant properties of coated guava. The results of this study indicate that a polysaccharide-based edible coating mixed with BSO improved the quality parameters and extended the shelf-life.