Purpose: Lower limb alignment is crucial in total knee arthroplasty (TKA). Previous studies have shown that robotics and personalized three-dimensional (3D) preoperative planning could improve postoperative alignment accuracy compared with conventional TKA, but comparison between the above two techniques has never been reported. The purpose of this study was to compare the alignment and prosthesis positioning accuracy between robotics and personalized 3D preoperative planning in TKA.Methods: A consecutive series of patients who received TKA in our Center from September 2020 to January 2021 were enrolled. After 1:2 matching, 52 and 104 patients were eventually included in robotics group and personalized 3D preoperative planning group, respectively. Multiple postoperative alignment variables, operation time, tourniquet time, length of hospital stay, hemoglobin (Hb) decrease at 1 and 3 days after operation were recorded and compared.Results: Compared with personalized 3D preoperative planning, robotics had significantly lower frontal tibial component (FTC) angle absolute deviation (P<0.001) and less FTC outliers (P<0.05). The postoperative hip-knee-ankle (HKA) angle and frontal femoral component (FFC) angle were different between two groups, while the absolute deviations were similar. Hb decreases of robotics were significantly lower than those of personalized 3D preoperative planning (P<0.001), while the operation time and tourniquet time were longer (P<0.001).Conclusion: Compared with personalized 3D preoperative planning, robotics has more accurate tibial component coronal alignment and less postoperative Hb decrease, while the operation time is significantly longer.Trial registration: The Chinese Clinical Trial Registry, ChiCTR2000036235. Registered 22 August 2020, http://www.chictr.org.cn/showproj.aspx?proj=59300