The use of cesarean section (CS) worldwide has increased to unprecedented levels. In Ethiopia, the CS delivery rate is above the rate recommended by the WHO. The postoperative pain experience is moderate to severe in most patients during their postoperative period. The administration of intravenous dexamethasone is thought to have an analgesic effect after surgery even though the analgesic profile of preoperatively administered dexamethasone is less addressed. This study aimed to assess the postoperative analgesic effect of preoperative intravenous dexamethasone for patients undergoing cesarean delivery under spinal anesthesia at Dilla University Referral Hospital, Southern Ethiopia. A double-blinded randomized controlled trial (RCT) was done on 112 patients undergoing elective CS under spinal anesthesia who were allocated randomly into normal saline and dexamethasone groups. Total analgesic consumption, time to first analgesic request, and postoperative pain score with the numerical rating scale (NRS) were followed for 24 h in both groups. Shapiro-Wilk tests were used to check normality. Independent samples t-test was used for the comparison of means between groups, Mann-Whitney U test for non-normally distributed data, and χ 2 test for categorical variables, and P-value <0.05 was considered statistically significant with a power of 80%. The finding of this study showed that the postoperative pain score of the dexamethasone group was significantly lower than the normal saline group at 2, 4, 6, 12, 18, and 24 h with a statistically significant P-value <0.05. There was also a significant difference in the time to the first rescue analgesic request between the two groups, with the dexamethasone group (median=347.5 min) and the normal saline group (median=230 min) with P=0.001. The authors conclude that preoperative administration of 8 mg of dexamethasone prolongs the first analgesic request time, decreases postoperative tramadol and diclofenac consumption, and decreases the postoperative pain score. The authors recommend that researchers conduct further RCTs with a different dose of dexamethasone and on a multicenter basis.