A comprehensive numerical investigation of fluid stream and laminar forced convection were conducted to simulate the effects of the semi-porous fins, which are a new combination of porous and solid parts, inside a partially heated channel with a staggered arrangement. The present numerical approach is based on the Navier-Stocks and Darcy-Brinkman-Forchheimer equations in the fluid and semi-porous regions, respectively. The effects of various parameters such as Reynolds number, Darcy number, fin height, and aspect ratio of the porous region’s height to total fin height were studied. Also, the effects of these parameters are illustrated further as a variation of dimensionless pressure penalty and heat transfer enhancement ratio in the flow domain. The results demonstrate that using a new type of fin with both solid and porous parts in a single fin, enhances the heat transfer up to 6% compared to the porous fin and decreases the pressure penalty up to 23% compared to the solid fin at Darcy number of 10−4 when the percentage of aspect ratio is equal to 20%. Furthermore, it was found that the Darcy number of 10−5 is a critical value for the optimum utilization of semi-porous fins.