Lack of consensus exists on the use of cementless total knee arthroplasty (TKA) in patients with knee osteonecrosis. Therefore, this study was conducted to evaluate (1) implant survivorship; (2) clinical outcomes and complications; and (3) radiographic outcomes of primary cementless TKA in knee osteonecrosis. This study included 46 patients (49 knees) who had knee osteonecrosis and underwent primary cementless TKA and had a mean follow-up of 44 months (range 36-96). Kaplan-Meier analysis was used to evaluate implant survivorship. Follow-up was performed post-operatively at 6 weeks, 3 months, and annually thereafter. Clinical outcomes including the Knee Society Scores (KSS) for pain and function, changes in range-of-motion, complications, and radiographic outcomes were analyzed. Aseptic implant survivorship was 97.9% (95% confidence interval 1.01-0.93) and all-cause implant survivorship was 95.9% (95% confidence interval 1.01-0.9), with 1 septic and 1 aseptic failures. The mean KSS for pain was 93 points (range 85-100) and the mean KSS for function was 84 points (range 70-90). Additionally, 1 patient had superficial wound necrosis and was treated with local wound care with no further sequela. Otherwise, no evidence of loosening, subsidence, or progressive radiolucencies were noted on radiological evaluation. Excellent implant survivorship, clinical, and radiographic outcomes of primary cementless TKA in the setting of knee osteonecrosis was demonstrated. Although further long-term study is needed to validate survivorship, new generation cementless TKA implants provide promising results in this subset of patients.