A von Neumann regular ring, named after John von Neumann for his work related to continuous geometry and operator algebras, has various equivalent characterizations in terms of popular properties of rings and modules. This paper mainly focuses on effective aspects of characterizations of von Neumann regular rings, and studies such characterizations by techniques of reverse mathematics. For not necessarily commutative rings, we obtain that $\mathrm{RC}{A}_0$ proves that a ring R is von Neumann regular iff every ${\mathrm{\Sigma }}_1^0$ finitely generated left ideal of R is generated by an idempotent iff every ${\mathrm{\Sigma }}_1^0$ cyclic left R-module is Lam-divisible. For commutative rings, we obtain that over $\mathrm{RC}{A}_0$, $\mathrm{WK}{L}_0$ (resp., ${\mathrm{ACA}}_0$) is equivalent to the statement that a commutative ring R is von Neumann regular iff the localization of R at any prime ideal (resp., maximal ideal) exists and it is a field. Lastly, we show that $\mathrm{AC}{A}_0$ proves that a commutative ring R is von Neumann regular iff every simple R-module is Lam-divisible.