Haricot bean is among the crucial food and cash grain legumes crops and have immense marketing potential in the world. It plays an important role in enhancing income and thereby ensuring the food security status of farm households. Despite such potential, a formidable marketing challenge faced in Kucha district of Southern Ethiopia. Cross-sectional 378 haricot bean-producing farm households were selected using four-stage sampling techniques. We used simple descriptive statistics, Heckman two-stage and multivariate Probit models to identify determinants of both market participation and outlet choices decisions of the farm household. The result shows about 85% of interviewed farmers have participated in selling haricot bean to market and the level of participation was found to be 65%. The key determinants of the market are the quantity of the haricot bean, extension service, average lagged year price of haricot bean, market information, and level of education of the household head were the main variables affected market participation decision of farmers while the extent of market supply affected by sex, family size of household, extension service, distance to all weathered road and the total quantity of output supplied to the market in 2019. The study suggests that strategies aiming for enhancing haricot bean market supply with appropriate market outlet choices should encourage farmers cooperative and linking them with terminal markets, enhancing yield, capacity building form production up to post-harvest handling, providing reliable and timely market information and improving poor road infrastructure must be considered while developing strategies for the improvement of the marketing system.