Plasmonic nanomaterials (PNMs) featuring localized surface plasmon resonance (LSPR) have significant thermal and non-thermal consequences. Although, nonthermal phenomena have already been extensively researched, the study of strongly localized photothermal heating is emerging. In the past few decades, the emerging field of thermoplasmonics which aims to leverage NMs LSPR capabilities for localized nano-heating applications has drawn greater interest. The objective of this study is to explore the nano-heating phenomenon of magnetic alloy nanocomposites, specifically Fex-Co1-x, Fex-Ni1-x, and Cox-Ni1-x having distinct configurations (Viz., \(x = 0.25, 0.50, \,{\text{and}}\, 0.75\) ), coated with Au and Ag shells. Examining the impact of nanoparticle (NP) composition and size, the study delves into nano-heating through LSPR phenomena in magnetic nanocomposites (MNCs) surrounded via water ambience. In optical simulations, the core radius of encapsulated magnetic alloy nanospheres varies from 10 to 40 nm, with a fixed shell thickness of 10 nm. The PyMielab V_1.0 simulation tool has been exploited for optical modeling. The presence of Au and Ag shell coating facilitates the tuning of plasmonic resonance in MNCs over a wide range by varying the composition of Fe, Co and Ni alloys. MNCs find importance in a variety of biomedical applications, playing key roles in targeted drug delivery, biosensors, magnetic resonance imaging (MRI), and facilitating magnetic hyperthermia therapy. However, MNCs act as potent nano-source of thermal energy at plasmonic resonance, making them potentially useful for photothermal applications.