Background: AIDS-related Kaposi sarcoma (AIDS-KS) remains a leading cause of morbidity and mortality among people living with HIV in Africa. Mortality among people with AIDS-KS on antiretroviral therapy remains high compared with people on antiretroviral therapy who do not have AIDS-KS. Setting: People living with HIV with Kaposi sarcoma (KS) who participated in 2 randomized trials (A5263/AMC066 [advanced stage] and A5264/AMC067 [mild-to-moderate stage]) conducted by AIDS Clinical Trials Group/AIDS Malignancy Consortium in low- and middle-income countries. Methods: We estimated mortality rates over the trial period. Cox proportional hazards regressions were used to identify baseline characteristics associated with mortality and compared mortality rates between participants who had KS progression within 12 weeks of treatment initiation (early progression of KS [KS-PD]) and those who did not. Results: Of the 329 and 189 eligible participants in A5263/AMC066 and A5264/AMC067, 71 (21.6%) and 24 (12.7%) died, respectively. In both trials, hypoalbuminemia was associated with increased hazards of death compared with normal albumin; A5263/AMC066: mild hypoalbuminemia (adjusted hazard ratio [aHR] = 3.01; 95% CI: 1.42 to 6.29), moderate hypoalbuminemia (aHR = 5.11; 95% CI: 2.54 to 10.29), and severe hypoalbuminemia (aHR = 14.58; 95% CI: 6.32 to 35.60), and A5264/AMC067: mild hypoalbuminemia (aHR = 5.66; 95% CI: 1.90 to 16.93) and moderate hypoalbuminemia (aHR = 7.02; 95% CI: 2.57 to 19.15). The rate of death was higher among participants who had early KS-PD than those without early KS-PD in A5263/AMC066 (HR = 5.09; 95% CI: 1.71 to 15.19) but not in A5264/AMC067 (HR = 1.74; 95% CI: 0.66 to 4.62). Conclusions: Albumin measurements may be used to identify individuals at higher risk of death after initiating KS treatment and for evaluation of interventions that can reduce AIDS-KS mortality.