Alfalfa fibrous residues (AFR) are the primary by-product of alfalfa leaf protein (LP) extraction after blending chopped whole plant alfalfa. The AFR is typically difficult to ensile due to high moisture and low water-soluble carbohydrate (WSC) concentrations. The objective of this study was to determine the effect of adding corn flour (CF) or apple pomace (AP) to AFR on the ensiling characteristics, fermentation quality, microbial population, nutritive value, and proteolysis. The AFR was made from second cutting alfalfa harvested at a vegetative stage. After extracting LP, AFR was mixed without additives (Control) or with corn flour (CF) or apple pomace (AP) at 5%, 10%, and 15%, on a fresh weight basis in triplicate and packed in laboratory silos (40 cm high × 30 cm) at a density of 750 g L⁻¹ and was stored in the dark for 60 d. Data were analyzed using the ANOVA procedure of SAS. The DM, lactic acid concentration, and in vitro DM digestibility (IVDMD) of ensiled AFR linearly increased whereas pH, buffering capacity, and acetate concentrations linearly decreased with incremental inclusion of CF or AP (P < 0.01). The counts of lactic acid bacteria and fungi linearly decreased with inclusion of CF or AP (P < 0.01). The WSC concentration and total bacteria counts linearly reduced (P < 0.01) with incremental inclusion of CF but linearly increased (P < 0.01) with inclusion of AP. Crude protein, ammonia-N/total-N, and non-protein N/total N (NPN/TN) decreased with incremental inclusion of CF or AP (P < 0.01). Concentrations of NPN/TN were lower when AP was applied instead of CF (P < 0.05). Ensiling AFR with CF or AP improved fermentation quality and IVDMD of silages, and reduced proteolysis. Adding AP was more effective than CF at inhibiting proteolysis in AFR.