The Multi-Trait selection index (MTSI) has been used to select highly productive and stable faba bean landraces across various traits. Fifteen productive, morphological, and phenological traits with desired and undesired selection gains (SGs) were evaluated in fifteen faba bean landraces under Mediterranean field conditions between 2019–2021. According to our results, most of the faba bean traits are influenced by the genotype × environment interaction (GEI) effects. Banner length (BL), seed yield (SY), diameter (D), number of flowers per inflorescence (NFI), branch number (BRN), and 100 seed weight (HSW) were found to be highly influenced by the environment, the proportions of variance explained by environmental factors were arranged between 83.21% and 74.08%, and only seed number per pod (SNP) was the highest genotypic effect (54.02%). According to the MTSI index, only three landraces (Gaada Mascara (G4), Oued zentai (G13), and Khmakhem (G15)) were considered to be highly yield-productive and to have a broad adaptability across Mediterranean environments. When numerous traits were evaluated, the MTSI index provided a strong and powerful tool for developing improved selection techniques for Faba bean studies.