The significant and inherent limitations associated with commonly used methods of in vitro embryoid body (EB) formation motivate the development of novel, facile, efficient and reproducible techniques. In this study we report the possibility of using “liquid marbles” as facile and efficient micro bioreactors for in vitro EB formation. To exploit liquid marbles as micro biological reactors, embryonic stem cells (ES cells) were inoculated into liquid marbles containing embryonic cell growth medium. Herein we show how the confined internal space of a liquid marble, along with the porous and non-adhesive properties of the highly hydrophobic liquid marble shell, can provide the necessary conditions for the formation of uniform EBs inside liquid marbles. Factors such as the powder particle size, the liquid marble volume and the cell seeding density inside each liquid marble were also investigated to evaluate the effects of varying experimental conditions on the efficiency of EB formation within a liquid marble.