In this study, brewer’s spent grains (BSG)-raw matrix was technologically and functionally improved by adding natural active ingredient carriers (crushed wheat, rapeseed, and pumpkin seed press cake) and using planetary roller extrusion and used as feed additive for pigs. Feeding trials were run for 189 days using 60 pigs with an age of 28 days. Pigs were grouped in a control group (fed with organic basic feed) and two experimental groups (fed with BSG 1 or BSG 2 in addition to organic basic feed). The 20 animals per group gained similar weight in the control group (306 g day⁻¹ and 725 g day⁻¹) and in the group fed with BSG 1 (282 g day⁻¹ and 627 g day⁻¹) or BSG 2 (250 g day⁻¹ 598 g day⁻¹) in addition during rearing and fattening phases, respectively. Carcass evaluation revealed that meat quality did not differ between control and experimental groups. The BSG-based feed formulations tested seem to not result in negative effects on weight gain nor on meat quality. Animals were generally of good health and marketable quality, and thus the outcomes of this study are expected to contribute to an improved utilization strategy of brewer’s spent grains from breweries.