Biochar, a carbon-rich material derived from biomass pyrolysis, has gained considerable attention as a soil amendment for improving soil fertility and crop productivity. One of the key benefits of biochar is its ability to mediate soil acidity, influencing soil pH and buffering capacity. Biochar can act as a liming agent, raising soil pH in acidic soils, or as an acidifying agent, lowering pH in alkaline soils, through its alkaline or acidic functional groups, respectively. This property makes biochar a versatile tool for managing soil acidity in different agricultural systems. The application of biochar to acidic soils can enhance crop performance by improving nutrient availability, reducing toxic metal concentrations, and promoting microbial activity. Biochar can also increase the cation exchange capacity (CEC) of soils, leading to improved nutrient retention and reduced leaching losses. Furthermore, biochar-mediated enhancement of soil pH can promote the dissolution of minerals and the release of essential plant nutrients, such as phosphorus, calcium, and magnesium, which are often limited in acidic soils. Apart from influencing soil acidity and crop performance, biochar can also improve other soil properties. Biochar can enhance soil water holding capacity, reduce soil erosion, and increase aggregate stability, thereby improving soil structure and fertility. Biochar can also sequester carbon in the soil, contributing to climate change mitigation by reducing greenhouse gas emissions. In this review, we summarize the current state of knowledge on the effects of biochar on soil acidity, crop performance, and soil properties. Overall, biochar-mediated enhancement of soil acidity can have profound positive effects on crop performance and soil properties, making it a promising soil amendment for sustainable agriculture.