This study revealed that 54.6% [95% CI 49.6–59.6] of adult clients were satisfied with ART services given at Woliso Town. This is consistent with previous studies in Mizan-Tepi and West Wolega Zone [7, 8]. However, this finding was lower than the study reported from Gonder Town (75.4%), and Jimma town (89.6%) [9, 10].

The statistically significant associations were found between overall client satisfaction and respondents’ education level, differentiated service delivery model, waiting time, and health education information. Clients who had not attended formal education were 86.2 percent times less likely to be satisfied compared to those who had attended formal education. This is consistent with the studies conducted in Nigeria, Mizan Tepi, and Gondar University referral hospitals in Northwest Ethiopia [4, 7, 11]. On the other hand, clients who had attended health education information had higher odds of being satisfied; they were 3.2 times more likely to be satisfied than those who had not attended health education information. This is consistent with the studies conducted in Nigeria, Eastern Ethiopia, and Addis Ababa Zewditu Hospital [4, 12, 13].

In terms of waiting time, clients who waited less than 30 min to get services were 2.6 times more likely to be satisfied than those who waited more than or equal to 30 min. This is congruent with the studies conducted in Anambra State, Nigeria; Diredawa, eastern Ethiopia, and Hadiya Zone southern Ethiopia [14,15,16].

Related to the DSDM, clients who were on the ASM were 4.33 times more likely to be satisfied than clients who were on 3MMD during their last follow-up visits. Regarding the adherence status of clients, there was no association between overall client satisfaction and adherence status among adult clients attending ART clinics in Woliso town. In contrast, a study conducted in Africa found that clients who had good adherence were moderately satisfied compared to those who had poor adherence [17].