Mixed convection plays a crucial role in numerous technological applications due to its practical implications. This study focuses on investigating the thermofluidic phenomena in an open chamber designed in the shape of a butterfly, where the lower triangular wall is hot, and the upper inverted triangular wall is cold. The transport phenomena in this intricate geometry are analyzed using finite element-based computation. The study aims to examine the flow properties and heat transfer capabilities of a complex ventilated geometry filled with Co-kerosene nanofluid under mixed convection conditions. By considering the interplay between forced and natural convection, the numerical solver accurately simulates the convective processes occurring within the butterfly-shaped cavity. The regulating parameters for evaluating the overall thermal performance include the Hartmann number (Ha), Rayleigh number (Ra), Reynolds number (Re), and the wing angles of the cavity (Θ). Additionally, the impact of nanoparticle concentration is examined. The findings of this study provide insights into the convective velocity and heat transfer properties of the butterfly-shaped cavity in the context of mixed convection. Overall, a higher fluid velocity, lower magnetic field intensity, and moderate thermal gradient, along with a lower angle of the butterfly angle, correspond to lower irreversibility production and thus higher heat transfer (up to 101%). This analysis contributes to the design and optimization of heat transfer systems operating under similar complex circumstances and geometries.