This study assessed the influence of wilting, lactobacillus (LAB) and / or molasses on the chemical composition, phenolic compounds, in situ degradability and in vitro ruminal fermentation parameters of amaranth (var. Maria) silage using a randomized complete block design with 6 replicates. Treatments were fresh amaranth forage (FAF), ensiled amaranth without additive (EA), EA inoculated with LAB (EAB), EA + 5% of molasses (EAM), EA inoculated with LAB + 5% of molasses (EABM) and 24-h wilted EA (WEA). The ensiled materials were stored anaerobically for a period of 45 d. Chemical composition, oxalic acid and nitrate levels, silage fermentation characteristics, DM disappearance (DMD), OM disappearance (OMD), in vitro ruminal ammonia-N, VFA, cellulolytic bacteria and protozoa counts, and in situ DM and CP degradability were determined. Compared with FAF, EA had a lesser values of water-soluble carbohydrates (P = 0.023), nitrate (P = 0.001), total phenolics (P = 0.04), total tannins (P = 0.01), DMD (P = 0.01), ruminal cellulolytic bacteria (P = 0.02), soluble and very rapidly degradable fraction (P = 0.014), and effective degradability (P = 0.01). The EA had lesser OMD and CP degradability compared with FAF (P < 0.05). Adding molasses to EA resulted in increased ash and lactate concentrations and decreased ammonia (P < 0.05), but had no effect on OMD. The WEA had lesser ammonia and greater lactate compared to EA (P < 0.05). Overall, fresh amaranth var. Maria can be preserved as a valuable silage to feed ruminants. Ensiling amaranth var. Maria decreased the anti-quality compounds, and molasses addition improved the fermentation quality of the silage.