Due to its favorable properties, soybean meal (SBM) is used especially in young growing animals. In terms of sustainability, there are various efforts to reduce the amounts of SBM in compound feeds and to increase the use of regional protein sources. This paper focuses on the effects of a partial to total substitution of SBM by regionally produced rapeseed meal (RSM) in different piglet diets regarding 10 important factors having an impact on the environment. Four diets, characterized by different shares (%) of both protein-rich ingredients (SBM/RSM: 18.1/0; 13.6/6.70; 8.10/16.1; 0/28.0), were fed to four groups of 10 piglets each in two runs. The impact was calculated related to feed (per t) and was performance-based for every piglet (impact·kg weight gain−1) for each factor using methods according to life-cycle-analyses (LCA). Although feed intake and weight gains were not affected negatively, higher feed conversion ratios occurred, with high amounts of rapeseed inclusion. Nevertheless, the performance-based negative influence on climate change (kg CO2 eq·kg weight gain−1) was nearly halved when SBM was replaced by RSM. Since performance was not negatively affected, the use of RSM instead of SBM in piglet diets could be a viable tool for markedly reducing the negative impact on climate change.