The study examined the determinants of market outlet choices among smallholder Irish potato growers in Mbeya District. A two-stage random sampling method was used to select 288 smallholder farmers for primary data collection. The data were analysed using Stata version 15, and the multivariate probit model was applied to assess the factors influencing market outlet selection. The findings showed that the probability of Irish potato farmers choosing blocker, wholesaler, local, and retailer outlets was 32.1%, 31.6%, 28.5%, and 22.3%, respectively. This indicates that blockers were the most commonly chosen outlets, while retailers were the least preferred. The joint probability of farmers opting for all four market outlets was 0.6%, lower than the likelihood of not selecting all four outlets (16.7%). The multivariate probit model results revealed that several factors, including the age of the household head, education level, farm size, distance to the nearest market, availability of market information, access to extension services, and access to credit, had significant effects on farmers' market outlet choice behaviour. Based on these findings, the study recommended improving the current production systems, encouraging farmers to adopt intensive cultivation methods, and ensuring better prices for farmers as important strategies for making informed market outlet decisions. Furthermore, the study emphasised the need for policy measures that strengthen infrastructure development, such as creating market centres closer to farmers' locations and promoting farmers' groups to facilitate better market access.