This pooled analysis of randomized controlled studies investigated the safety and efficacy of onabotulinumtoxinA in male and female patients with overactive bladder (OAB). Data were pooled from four similarly designed trials in North America and Europe. Adults with idiopathic OAB for ≥6 months inadequately managed by at least one anticholinergic were randomized 1:1 or 2:1 to receive onabotulinumtoxinA 100 U or matched placebo in Cycle 1 and could request open-label retreatment with onabotulinumtoxinA 100 U at ≥12 weeks. Efficacy outcomes at Week 12 included the primary endpoint of mean urinary incontinence (UI) episodes per day and other variables, such as the proportion of patients with ≥50% reduction in daily UI episodes. Safety was assessed by monitoring treatment-emergent adverse events (TEAEs). Analyses by sex were descriptive. Males were further analyzed by benign prostatic hyperplasia (BPH) diagnosis status. In the pooled population (N = 1564), there were 194 males (12.4%) and 1370 females (87.6%). Mean number of baseline UI episodes per day was 4.9 in males and 5.5 in females. At Week 12, numerically greater mean reductions from baseline in number of daily UI episodes were observed with the onabotulinumtoxinA 100 U group (females: -3.0; males: -2.2) versus placebo (females: -1.1; males: -1.3). Achievement of ≥50% reduction in daily UI episodes was numerically greater with onabotulinumtoxinA 100 U (females: 64.8%; males: 61.2%) versus placebo (females: 30.6%; males: 44.8%), and numerically higher in males without BPH (onabotulinumtoxinA: 65.1%; placebo: 50.9%) versus with BPH (onabotulinumtoxinA: 54.3%; placebo: 36.6%). A total of 34.7% of males and 39.4% of females experienced at least one TEAE in the first 12 weeks during treatment Cycle 1. Urinary tract infection rate was 13.1% in females and 4.2% in males; incidence of hematuria was 6.8% in males and 1.1% in females. Incidence of urinary retention (defined as incomplete emptying, requiring catheterization) was 2.7% in females and 4.7% in males. OnabotulinumtoxinA 100 U was efficacious and well tolerated in men and women with OAB, including in males with and without BPH. No new safety findings were identified when data were analyzed by sex.