This study presents temperature distribution and heat performance of the longitudinal porous fins with rectangular, trapezoidal, and concave cross-sectional areas exposed to heat convection, conduction, and temperature-dependent heat generation simultaneously. The developed strongly nonlinear differential equation was solved using least square method (LSM). The radiation heat transfer from porous fin was taken into account and simulated using Roseland model. Parameters including heat flux, fin efficiency, and volumetric fin performance were used to compare fins with each other. Also, Radiative–Conductive, Convective–Conductive, Conductive–Radiative, Darcy number, Modified Rayleigh number, Heat Generation, and flow regime were discussed comparatively. The accuracy of the results of the approximate analytical method used is established via comparison with the results of numerical method.