Inorganic arsenic (iAs) is a recognized environment-related factor for bladder cancer (BCa). Arsenic (+3 oxidation state) methyltransferase (AS3MT) gene might influence BCa by regulating iAs metabolism. The objectives of the present study were to systematically review eligible case-control studies about AS3MT polymorphisms and BCa and to further compare the genotype distribution and allele distribution between BCa patients and controls by meta-analysis for humans. Besides, to clarify the effects of AS3MT expression on BCa clinical outcomes and survival time, we also conducted a series of analyses based on The Cancer Genome Atlas (TCGA) dataset. Databases were systematically retrieved and we applied Stata software to perform meta-analysis. The registration of this study protocol is at PROSPERO and ID is CRD42019133947. Five articles were recruited and pooled results demonstrated that rs3740393 and rs11191438 polymorphisms were related to BCa risk in overall population (P<0.05) in the overall population. In addition, GG and GC genotypes in rs3740393 and GG genotype in rs11191438 might be the susceptibility genotypes for BCa. Results based on 168 BCa samples from TGCA indicated that patients with higher expression of AS3MT had poor overall survival time and AS3MT expression is an independent indicator for BCa survival. This study identified that AS3MT polymorphisms could affect BCa risk and AS3MT expression was pivotal in prognosis of BCa.