This study analyzes institutional buyers’ need for and intention to adopt B2B agricultural e-commerce in Manado City and the factors shaping that intention, using UTAUT extended with Trust. A quantitative explanatory approach was applied to institutional buyers across sectors including restaurants/cafes, hotels, hospitals, catering, modern markets and MBG kitchens; 115 of 120 responses were retained after screening for careless responding and analyzed by PLS-SEM in SmartPLS 4, with nine hypotheses tested via 5,000-subsample bootstrapping. Adoption intention is predominantly low: mean Behavioral Intention is 1.96 on a 1–5 scale (SD = 0.75), with 80.9% of respondents low or very low, 13.0% moderate and 6.1% high. Seven of nine hypotheses were supported. Ranked by total effect, the determinants are Effort Expectancy (β = 0.345; p = 0.003), Facilitating Conditions (β = 0.291; p = 0.020), Social Influence (β = 0.250; p = 0.001) and Trust (β = 0.235; p = 0.020). Performance Expectancy has no significant direct effect (β = −0.033; p = 0.803) but is the strongest antecedent of Trust (β = 0.438; p < 0.001), producing full mediation (indirect β = 0.103; p = 0.019). The model explains R² = 0.653 of Behavioral Intention and R² = 0.669 of Trust. Developers and local government should prioritize interface simplicity, logistics reliability and trust infrastructure over feature or price competition. Findings should be read with caution given narrow discriminant margins and a pronounced floor effect.