Attention to post-training start-up grants and monitoring and evaluation (M&E) mechanisms towards engaging youths in agricultural practices leave much to be desired around the world and most especially in Nigeria, thereby, causing low agricultural productivity. Therefore, this study evaluated the influence of post-training start-up grants and M&E mechanisms on sustainable agricultural practices among youth agripreneurs in Southwest Nigeria. The study adopted cross sectional survey design and used proportional stratified random sampling technique to ensure representative sample. Out of the population of 9,099, 369 youths were sampled in the three selected states (Oyo, Ogun and Ekiti) who have participated in youth-focused agribusiness projects and programs funded by national and international development partners and managed by IITA. Reliability tests carried out on the instruments yielded Cronbach’s Alpha of between 0.713 and 0.799. Data were analyzed using descriptive (bar charts) and inferential (multiple regression analysis) statistics. Findings revealed that post-training start-up grants (β = 0.18, t = 3.44, p < 0.05) and M&E mechanisms (β = 0.37, t = 7.06, p < 0.05) had positive and significant effects on the adoption of sustainable agricultural practices among youth agripreneurs in Southwest Nigeria. The study concluded that post-training start-up grants and M&E mechanisms had significant effects on the adoption of sustainable agricultural practices among youth agripreneurs in Southwest Nigeria, Therefore, the study recommends that timely and sufficient financial resources be allocated for post-training grants targeting youth in agribusiness, alongside the mandatory adoption of robust M&E systems in agribusiness training programs to ensure sustainability outcomes. .