The article presents the possibilities of using by-products from the agri-food industry in the form of fruit and vegetable pomace as a supplementary ingredient to extruded food products in the form of snack pellets. In the recipe based on potato starch, pomace from apples, chokeberries, pumpkin, nigella seed and flaxseed were added in amounts of 10%, 20% and 30%. The prepared raw material blends were processed using a single-screw extruder-cooker with a plastification system L/D = 20 and variable screw speed. The aim of the research was to determine the effect of pomace addition on the extrusion-cooking process, i.e., efficiency and energy consumption, as well as on selected physical properties of the obtained food pellets, such as expansion index, bulk density and durability. The addition of selected pomace influenced the extrusion-cooking process and the physical properties of the extrudates. A percentage contribution ranging from 10 to 20% can optimize the extrusion-cooking process and improve the quality characteristics of the final product, while simultaneously utilizing by-products from the agri-food industry and reducing their negative environmental impact.