Potassium (K) is an essential macronutrient for plant growth, yet its limited availability in soils poses a significant challenge to agricultural productivity. Despite its abundance, only 1–2% of soil K is accessible for plant uptake, with the rest locked in mineral forms. While K fertilizers address these deficiencies, their excessive use raises environmental and economic concerns. Sustainable alternatives, such as potassium-solubilizing microbes (KSMs), offer a promising solution by enhancing K bioavailability through mineral dissolution and organic acid production. Microbial species like Bacillus mucilaginosus not only release K but also improve soil health by solubilizing additional nutrients. This chapter emphasizes the potential of KSMs to reduce dependence on chemical fertilizers, promote eco-friendly farming, and support sustainable food production systems.