Background Neurogenic detrusor overactivity (NDO) affects the quality of life (QoL) of millions of individuals worldwide. The purpose of this study was to assess the efficacy and safety of onabotulinumtoxinA in patients with NDO using a network meta-analytic approach, which can also quantify and compare the efficacy of onabotulinumtoxinA across different dosages. Methods PubMed, EMBASE, and the Controlled Trials Register were searched to identify randomized controlled trials comparing onabotulinumtoxinA to a control for NDO in adult patients. The primary outcome was the mean number of urinary incontinence (UI) episodes per week. Urodynamic parameters included the maximum cystometric capacity (MCC) and the maximum detrusor pressure (MDP). The safety of onabotulinumtoxinA was determined by the incidence of various frequent adverse events (AEs). Two authors extracted data independently, and the statistical analyses were performed using RevMan 5.1.0 software. Results A total of 1,915 patients from six randomized controlled trials were included in this meta-analysis. The onabotulinumtoxinA-treated groups had a significantly decreased mean number of urinary incontinence episodes per week (at week 6) (onabotulinumtoxinA200U: MD: -10.72, 95% CI: -13.4 to -8.04, P<0.00001; 300 U: MD: -11.42, 95% CI: -13.91 to -8.93, P<0.00001), MDP (200 U: MD: -33.46, 95% CI: -39.74 to -27.18, P<0.00001; 300 U: MD: -31.72, 95% CI: -37.69 to -25.75, P<0.00001), and greater increased MCC (200 U: MD: 141.30, 95% CI: 121.28 to 161.32, P<0.00001; 300 U: MD: 151.39, 95% CI: 130.43 to 172.34, P<0.00001) compared to the placebo-treated groups. However, there were no significant differences between the onabotulinumtoxinA-treated groups for the number of weekly UI episodes at 6 weeks (MD: 0.08, 95% CI: -2.57 to 2.73, P = 0.95). Similarly, we also observed that there were no significant differences in MCC (MD: -9.97, 95% CI: -33.15 to 13.20, P = 0.40) and MDP (MD: -1.86, 95% CI: -8.09 to 4.37, P = 0.56). Considering the AEs, the onabotulinumtoxinA-treated groups were often associated with more complications, including urinary tract infections (UTIs) (RR: 1.47, 95% CI: 1.29 to 1.67, P<0.00001), urinary retention (RR: 5.58, 95% CI: 3.53 to 8.83, P<0.00001), hematuria (RR: 1.70, 95% CI: 1.01 to 2.85, P = 0.05), and muscle weakness (RR: 2.59, 95% CI: 1.36 to 4.91, P = 0.004). Conclusions OnabotulinumtoxinA can significantly reduce the frequency of urge urinary incontinence and improve urodynamic parameters (MCC and MDP) in patients with NDO at 6 weeks after treatment. This meta-analysis indicates that onabotulinumtoxinA is effective and safe for treating patients with NDO compared to placebo. Additionally, we did not observe any statistical or clinical differences in efficacy between 300 and 200 U dosages.