High-oil corn (HOC, >6% oil) is associated with increased germ size, which can be accompanied by greater accumulation of bioactive compounds such as phenolics. This study compared the phenolic content, antioxidant capacity (AC), and α-glucosidase inhibitory activity (αGI) of HOC and commercial corn hybrids. Twelve HOC hybrids (eight white, four yellow) obtained from doubled haploid lines and three normal corn hybrids (white) were used. Methanolic extracts were analyzed for total phenolics (Folin–Ciocalteu), flavonoids (AlCl₃), AC (ABTS, DPPH), phenolic profiles by liquid chromatography–mass spectrometry, and αGI. All HOC hybrids met the test weight (≥73 kg/hL) required for nixtamalized products. They showed great variability in total phenolics, total flavonoids, and AC; the white HOC hybrid NWP19xNWP81 showed the highest values, significantly higher than those of commercial hybrids. Phenolic profiles showed 19 compounds, mostly ferulic acid derivatives; the NWP19xNWP81 hybrid showed the highest content of most of them. The levels of 15 compounds correlated positively with the AC. Eight HOC hybrids showed higher αGI than the commercial hybrids, highlighting BYP103xNYP135 (yellow). Some compounds (e.g., dehydrodiferuloyl diarabinofuranoside and dimethyl dehydrodiferuloyl diarabinofuranoside) showed high affinity for α-glucosidase. These results suggest that some HOC hybrids have superior nutraceutical quality, and their use as food or feed could provide better health benefits than normal corn.