Nanobubble drip fertigation (NDF) integrated with bio-ameliorant (BA), as an innovative and appropriate technology, sustainably restores soil health, enhances nutrient availability, and improves yield and quality of chili as a high-value cash crop at an efficient cost for small farmers. This study aims to comprehensively assess the synergistic effects of nanobubble fertigation technology and bio-ameliorant on the growth, yield, quality, and grading of chili cultivated in soil media within a simple plastic house structure. The experiment was set up as a strip plot consisting of nutrient delivery methods (conventional fertilizer (CF)= NPK 300 kg ha⁻¹, drip fertigation (DP)= 1600 ppm, and NDF= oxygenated DF with 6.5 mg L⁻¹ dissolved oxygen (DO) and soil amendments (conventional soil amendment (CS)= cow manure 20 t ha⁻¹, BA = bio-ameliorant 4 t ha⁻¹, A= ameliorant 4 t ha⁻¹)) and provided three replications. Results revealed that oxygenated DF, combined with 6.5 mg L⁻¹ DO and BA, significantly enhanced soil nutrient availability and microbial activity. This treatment notably improved chili fruit quality, achieving a 79.33% Grade A, and increased fruit number and weight. Correlation and principal component analysis analyses confirmed strong relationships between soil biochemical parameters and yield components, while path analysis identified fruit number as the primary determinant of total yield. The findings offer a sustainable and efficient alternative to conventional fertilization, providing practical insights for smallholder farmers aiming to optimize chili productivity and quality through integrated soil and nutrient management strategies.