Background: Crizotinib and alectinib are the 2 most commonly used anaplastic lymphoma kinase (ALK) inhibitors for ALK-positive non-small cell lung cancer (NSCLC). We compared their antitumor efficacies and adverse effects based on a pooled analysis of the ALEX, ALESIA, and J-ALEX clinical trials. Methods: Seven databases were searched for eligible articles. The primary endpoints included overall survival (OS), progression-free survival (PFS), central nervous system (CNS)-PFS, drug responses, and adverse effects (AEs). Results: Seven articles on 3 randomized controlled clinical trials (ALEX, ALESIA, and J-ALEX) that included 697 patients were included. Compared with crizotinib, alectinib exhibited superior efficacy in PFS (HR [hazard ratio]: 0.35 [0.25–0.49], p < 0.00001), OS (HR: 0.66 [0.47–0.92], p = 0.02), CNS-PFS (HR: 0.17 [0.11–0.24], p < 0.00001), duration of response (HR: 0.31 [0.23–0.42], p < 0.00001), objective response rate (risk ratio [RR]: 0.87 [0.80–0.94], p = 0.0003), partial response (RR: 0.88 [0.81–0.96], p = 0.004), and grade 3–5 AEs (RR: 1.43 [1.09–1.87], p = 0.009). Additionally, compared with crizotinib, alectinib exhibited a survival advantage that increased with its prolongation of survival time. The disease control rate, complete response, and total AEs were comparable between the 2 groups. The crizotinib group reported higher rates of constipation, nausea, diarrhea, vomiting, peripheral edema, dysgeusia, visual impairment, and levels of alanine aminotransferase and aspartate aminotransferase as well as greater decreases in appetite and neutrophil count. Conclusions: In both antitumor efficacy and safety, alectinib appears to be superior to crizotinib for the treatment of ALK-positive NSCLC.