<p>Extensive studies have investigated second-order singular differential equations to model various phenomena in astrophysics, reaction-diffusion processes, and electrohydrodynamics. However, finding numerical and analytical solutions for these problems with appropriate boundary conditions is challenging due to their inherent nonlinearity. Our current study explores singular second-order differential equations (SSODEs) with boundary conditions, specifically those modelling the distribution of heat sources in the human head and the steady-state temperature distribution in a vessel before a thermal explosion. The fundamental idea behind our approach is initially transforming the differential equation into an equivalent integral form, thereby circumventing the singular behaviour. Subsequently, the optimal homotopy analysis method is employed to scrutinize two distinct models, i.e., the heat conduction model, the thermal explosion model and the spherical catalyst equation. Further, a detailed convergence analysis is conducted in a Banach space framework to ensure the method’s reliability. The accuracy of the new approach is checked by considering various numerical examples with different values of thermogenesis heat production, the Biot number, and metabolic thermogenesis slope. It has been shown that the proposed approach qualitatively and quantitatively approximates the solutions with higher precision than the existing Adomian decomposition method.</p>