Germination is an allied process to aggregate functional value to grains, specially increasing the content of phenolic compounds and antioxidant activity. Although, the health importance of phenolic compounds is known, their bioaccessibility is still a challenge to food science, due their instability through digestion. Therefore, the aim of this work was to evaluate phenolics composition from non-germinated and germinated black mustard flour and their antioxidant potential after simulated digestion, using the harmonized static in vitro digestion method for food: INFOGEST protocol. To achieve this objective, black mustard (Brassica nigra) was germinated at 25°C for 48 hours alternating light and darkness periods. Non-germinated and germinated grains were lyophilized, grounded and defatted to obtaining of mustard flours. The INFOGEST protocol was applied for oral, gastric and intestinal phases simulation. The digested and centrifuged fraction were investigated using the following methods: Total Phenolic Compounds (TPC); Ferric Reducing Antioxidant Potential (FRAP) and ABTS- and DPPH-radical scavenging activities. Additionally, the identification and quantification of some selected phenolic compounds were performed by High Performance Liquid Chromatography (HPLC). Digestion and germination as single processes increased significantly (p < 0.05) the TPC content (57 and 8%, respectively) and antioxidant activity (125% for ABTS and 35% for FRAP, respectively) of the mustard. However, TPC improvement promoted by germination was normalized with the digestion process. Phenolics profile changed as a result of both processes, corroborating with those positive increments. Gallic, 3,4-dihydroxibenzoic, vanillic, caffeic and sinapic acids were the most evident compounds involved in these changes after digestion and/or germination. This work encourages further investigations of black mustard phenolic compounds and their role as antioxidant molecules, since its antioxidant potential was found to be still remarkable after digestion.