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Soil acidity is a major global challenge that diminishes agricultural productivity by limiting nutrient availability and degrading agroecosystems. In Ethiopia, particularly in the mid and highlands, a large proportion of arable land is affected by soil acidity, severely restricting crop yields. Sustainable and effective soil amendment options are urgently needed to rehabilitate these acid-affected soils. This study investigated the individual and combined effects of lime, coffee husk vermicompost (CHVC), and chemical phosphorus (P) fertilizer on soil chemical properties and maize productivity in acidic Cambisols and Nitisols of Sayo District, western Ethiopia. Field experiments were conducted during the 2023/24 and 2024/25 cropping seasons using a randomized complete block design. Treatments included factorial combinations of three lime rates (0, 50, and 100% lime requirement), three CHVC rates (0, 3, and 6 t/ha), and three P fertilizer rates (0, 23, and 46 kg P₂O₅/ha), replicated three times. Soil samples were collected before planting and after harvest to evaluate changes in soil chemical properties, while agronomic data were recorded to assess maize yield and yield components. Both sole and integrated applications of lime, CHVC, and P fertilizer significantly (p < 0.05) improved soil chemical properties. The most effective treatment (100% LR + 6 t/ha CHVC + 46 kg P₂O₅/ha) raised soil pH from 5.07 (control) to 5.95 in Cambisols and from 4.71 (control) to 5.99 in Nitisols, while reducing exchangeable acidity from 2.13 to 0.16 and 2.83 to 0.20 cmol₊/kg, respectively. Available phosphorus increased to 7.05 mg/kg in Cambisols (28.4% increase) and 4.42 mg/kg in Nitisols (20.39% increase). Integrated amendments also enhanced soil organic matter from medium to high, total nitrogen from low to high, and increased exchangeable bases, while reducing micronutrient (Fe, Mn, Zn, and Cu) levels. Maize grain yield peaked under the full treatment, increased from 2.95 t/ha (control) to 9.15 t/ha in Cambisols (210% increase) and from 2.50 t/ha (control) to 7.03 t/ha in Nitisols (181% increase). Economic analysis confirmed the profitability of the integrated approach. The combined use of lime, CHVC, and P fertilizer is an effective, economically viable strategy for mitigating soil acidity and sustainably increasing maize productivity in western Ethiopia’s acidic soils and similar agro-ecologies.