The present study aimed to standardize germinated oat extracts (GOEs) by profiling avenanthramides (AVNs) and phenolic acids and evaluate their neuroprotective effects against Aβ-induced cytotoxicity in human neuroblastoma (SH-SY5Y) cells. GOEs were standardized to contain 1652.56 ± 3.37 µg/g dry weight (dw) of total AVNs, including 468.52 ± 17.69 µg/g AVN A, 390.33 ± 10.26 µg/g AVN B, and 641.22 ± 13.89 µg/g AVN C, along with 490.03 ± 7.83 µg/g dw of ferulic acid, using a validated analytical method. Treatment with AVN C and GOEs significantly inhibited Aβ-induced cytotoxicity ( < 0.05). Furthermore, both AVNs and GOEs markedly reduced Aβ-induced reactive oxygen species (ROS) generation in SH-SY5Y cells, showing significant scavenging activity at concentrations of 25 μg/mL (AVNs) and 50 μg/mL (GOEs) ( < 0.05). RT-PCR analysis revealed that AVNs and GOEs effectively downregulated the expression of inflammation- and apoptosis-related genes triggered by Aβ exposure. These findings suggest that GOEs rich in AVNs may serve as a potential functional ingredient for enhancing memory function through the inhibition of neuroinflammation and oxidative stress.