Microfluidic systems enable rapid diagnosis of diseases, biological analysis, drug screening, and high-precision materials synthesis. In spite of these remarkable abilities, conventional microfluidic systems are microfabricated monolithically on a single platform and their operations rely on bulky expensive external equipment. This restricts their applications outside of research laboratories and prevents development and assembly of truly versatile and complex systems. Here, novel magnetorheological elastomer (MRE) microactuators are presented including pumps and mixers using an innovative actuation mechanism without the need of delicate elements such as thin membranes. Modularized elements are realized using such actuators, which can be easily integrated and actuated using a single self-contained driving unit to create a modular, miniaturized, and robust platform. The performance of the microactuators is investigated via a series of experiments and a proof-of-concept modular system is developed to demonstrate the viability of the platform for self-contained applications. The presented MRE microactuators are small size, simple, and efficient, offering a great potential to significantly advance the current research on complex microfluidic systems.