The field of advanced nanotechnology is brimming with a plethora of nanotheranostics whose combinatorial synergistic applicability in treating malignant tumors is tremendous. But such multifunctional systems do hold drawbacks that are primarily liable to the inherent nature as well as the properties of the incorporated nanoparticles, which can be effectively tackled by either substituting or incorporating molecules having higher biocompatibility and biodegradability profiles. So, one such sort after, highly exploited inorganic nanocarrier using which theranostic platforms are developed is the Mesoporous Silica Nanoparticle (MSNs), whose amalgamation with upconversion nanoparticles having cutting-edge Near-Infrared imaging proficiency is gaining eminence in biomedicine-based research owing to its exemplary properties in drug targeting, bio-imaging and photodynamic/photothermal therapy, that makes them interesting for further research. MSNs are versatile in aspects related to their pore size and nature, greater drug loading efficiency, and functionalization accentuating their applicability. Several constructive studies with MSNs have been attempted by researchers worldwide, whose manipulation ultimately serves the said purpose of achieving a more holistic approach to treating carcinomas. This article principally sheds light on MSN-based hybrid nanotheranostics such as MSN-Metal Nanoparticles, MSN-Quantum Dots, MSN-Carbon Nanotubes, MSN-Fullerenes, MSN-Graphenes/ Graphene Oxide, MSN-Persistent Luminescence Nanoparticles, and MSN-Carbon-Dots, along with their designing strategies, characterization, applications, in vitro and in vivo efficacy, limitations, biotoxicity as well as the current challenges and future perspectives.