Nanogels (NGs), or small particles formed by physically or chemically crosslinked polymer networks, represent a niche in the development of “smart” nanoparticles for drug delivery and diagnostics. They offer unique advantages over other systems, including a large and flexible surface for multivalent bio-conjugation; an internal 3D aqueous environment for incorporation and protection of (bio)molecular drugs; the possibility to entrap active metal or mineral cores for imaging or phototherapeutic purposes; stimuli-responsiveness to achieve temporal and/or site control of the release function and biocompatibility. The availability of inexpensive and robust preparation methodologies is at the basis of the development of effective nanogel-based theragnostic devices. The design rules for mass fabrication of nanoscale hydrogel particles with the recourse to industrial-type accelerators is here discussed.