Gels play a significant role in our daily lives as they provide stability and desired features to various items of regular use, such as cosmetics, pharmaceuticals, household items, and agricultural products. However, a microbial attack on gels commonly occurs during gel-based formulations. Antibiotic-loaded gels can reportedly be stored for a long time. In this study, we fabricated a tetracycline-loaded gellan gum (TC/GG) gel and assessed its long-term stability against microbial attack. Morphological analyses revealed a firm and smooth texture with multifold bumpy surfaces on the GG and TC/GG gels. Fourier transform infrared spectroscopic analysis showed that the gel was well hydrated and thus suitable for releasing antibiotics. The feasibility of inhibiting microorganisms was qualitatively examined using the disk diffusion method. Interestingly, the unloaded GG gel itself exhibited an antimicrobial effect, while the loaded TC/GG gel showed a better antibacterial effect on S. aureus than on E. coli. TC/GG can be used to store and protect gels from microbial attacks for a long duration. In addition, it is suitable for storing bioactive agents, which are used in the biomedical field.