It is becoming increasingly clear that nanoparticles (NPs) possess many potential applications in both clinical medicine and research. Potential utilization of NPs in nanomedicine for the treatment of respiratory diseases where eosinophils exert pathogenic roles is gaining increasing attention. Even though several NPs were found to possess pro-inflammatory activities in in vivo models based on an increased number of eosinophils in rodent airways, it is not clear how NPs could directly activate eosinophils themselves and how they can alter their biology. In this review, we discuss the most recent data in this new area of research demonstrating that NPs could now be added as new eosinophils modulators. Indeed, activation of eosinophils with NPs could lead to modulation of spontaneous apoptosis, caspase activation, and cytoskeleton breakdown when apoptosis is induced; cytokine production, de novo protein synthesis, cellular adhesion onto a cell substratum, and cell signalling events such as activation of the phosphoinositide 3-kinase/Akt pathway and actin re-localization are involved in NP-induced adhesion. Therefore, future development of therapeutic strategies with NPs aiming at targeting diseases where eosinophils are involved should now consider the capacity of NPs to modulate human eosinophil biology.