Bladder cancer is a heterogeneous disease with variable natural history. Non-muscle-invasive bladder cancer has a favorable prognosis following transurethral resection, but the optimal adjuvant chemotherapy plan is still in debate. The aim of this study was to evaluate the effect of the adjuvant intravesical administration of a single dose of gemcitabine in the outcome of this disease. For that purpose, we performed a systematic review and meta-analysis on available randomized control trials on MEDLINE, EMBASE, Cochrane, Scopus, and Google Scholar databases. Ultimately, two studies were included with a total number of 654 patients. The statistical analysis performed showed that a single post-operative intravesical dose of gemcitabine does not affect the recurrence rate of non-muscle-invasive bladder cancer compared to placebo. Therefore, this therapeutic strategy does not offer any significant improvement on the outcomes of the disease. Nonetheless, due to the plethora of available therapeutic agents and treatment strategies, further research is needed to establish the optimal treatment in this category of patients.