Botulinum toxin A injection into the detrusor can reduce detrusor contractility, improve bladder compliance, and resume urinary continence. While a urethral injection of BoNT-A may reduce the urethral resistance and facilitate bladder emptying reducing postvoid residual (PVR) and frequent urinary tract infections. This work aims to provide cumulative data about the efficacy of Botulinum Toxin A (BoNT-A) in treating patients with Detrusor External Sphincter Dyssynergia (DESD). A systematic search was performed of PubMed, Cochrane library Ovid, Scopus & Google scholar to identify Urology RCTs, clinical trials, and comparative studies, which studied the outcome of Baseline assessment versus Follow-up assessment of DESD patients. A meta-analysis was done using fixed and random-effect methods. The main outcome measures were average PVR (postvoid residual), MDP (mean detrusor pressure), dLPP (detrusor leak point pressure), and MUP (mean urethral pressure). A total of 8 studies were identified involving 500 patients. Regarding outcome measures, the random-effects model of the meta-analysis study showed a highly significant decrease in mean PVR and MUP in follow up assessment compared to baseline assessment (p = 0.001). The fixed-effects model showed a highly significant decrease in mean MDP in follow up assessment (p < 0.001). The random-effects model of the meta-analysis study showed a non-significant difference in mean dLPP in follow up assessment (p > 0.05). To conclude, Botulinum toxin A injection proved its efficacy through reducing mean PVR, MDP, and MUP in the follow-up assessment, but we didn’t find a significant change in mean dLPP in the follow-up assessment.