This study presents the mixed convection inside a four-sided lid-driven square porous cavity whose right wall is maintained at a sinusoidal temperature condition, the left wall of the cavity is maintained at a cold temperature, while the top and the bottom walls are adiabatic. We have discussed two different cases depending upon the direction of the moving walls. Brinkmann-extended Darcy model is represented in terms of $$\psi $$ and $$\xi $$ using the stream function-vorticity formulation to simulate the momentum transfer in the porous medium. This formulation is used to solve the governing equations as a coupled system of equations which consists of the field variables, vorticity $$(\xi )$$ , stream function $$(\psi )$$ , and temperature (T). The velocity components (u, v) are derived from the stream function $$(\psi )$$ whereas the average Nusselt number is derived from temperature. The stability and consistency of the applied numerical scheme to the considered problem has been proven by matrix method. The numerical results are investigated by ranging the various dimensionless numbers such as Grashof number $$(10^3 \le { {Gr}} \le 10^5)$$ , Darcy number $$(10^{-1} \le { {Da}} \le 10^{-5})$$ , Reynolds number $$(10 \le { {Re}} \le 1000)$$ and keeping the Prandtl number $$({ {Pr}}=0.7)$$ fixed.