This research focused on the impact of two strains of probiotic Bifidobacterium spp. i.e., B. longum (Bg), or B. animalis subsp lactis (Bc) on post-acidification, the viable cell counts (VCC), total phenolic and flavonoid contents (TPC and TFC, respectively), and antioxidant activity of fermented (F) soymilk (SM), almond milk (AM), and their combination (100%, 75%, 50%, & 25%) during 0, 7, 14, & 21 days of storage. All fermented SM, AM, and their combination showed higher (p < 0.05) post-acidification than their respective controls during the storage. All samples showed VCC ranging between 6.9 and 7.4 log cfu/mL compared to their respective controls (3-4 log cfu/mL; p < 0.05). TPC in FSM/AM (50:50)-Bg & Bc was 2 folds higher (74.3 ± 0.021 & 61.34 ± 0.037 μg GAE/mL; p < 0.05) than control (22.52 ± 0.168) on day 21. The presence of Bg improved (p < 0.05) TFC in FSM (100) after 1 st day of storage. Both Bg and Bc had a positive impact on the antioxidant activity of all treated samples during storage. In conclusion, fermented soy and almond milk and their combination might serve as an effective vehicle for B. longum, or B. animalis subsp lactis with antioxidant activity.