This study examined and compared coffee production levels among smallholder farmers, those involved, and those not involved with Hanns R. Neumann Stiftung (HRNS) interventions since 2006. The study sample was selected using systematic and random sampling techniques, whereby 104 out of 413 respondents were selected from two wards and five villages within the HRNS intervention zone, as well as five villages without HRNS interventions; farmers in both groups being members of Umalila Agricultural Marketing Cooperatives (AMCOS) and Kyobo, Tutafika, and Ikuti AMCOS. The production levels were then compared for two samples in Mbeya and Rungwe Districts, respectively. Questionnaires, focus group discussions, and key informant interviews were used to collect primary data, which were complemented by secondary data from documentary reviews. Descriptive statistics, including frequencies, percentages, and means, were employed to analyse socio-economic characteristics and coffee production parameters. The study findings revealed that smallholder coffee farmers’ yields increased significantly with HRNS interventions, reaching 248.66 kg/ha, compared to 115.18 kg/ha for coffee farmers outside the HRNS intervention. The findings indicate that HRNS interventions have a positive impact on smallholder coffee farmers who are beneficiaries of the HRNS program. Thus, the findings highlight the critical significance of government assistance in sustaining such programs. The study recommends for sustained Tanzanian government support for HRNS-like interventions, such as the continual provision of quality seedlings, fertilizers, and extension services to enhance coffee production. This study contributes to the theoretical understanding of agricultural interventions by comparing smallholder farmers’ coffee production with and without HRNS interventions. It demonstrates the usefulness of HRNS in increasing yields, emphasizing the significance of focused interventions in coffee production.