Disclosed is the seed of a novel soybean variety, designated 09AY403123-1, a sample of which is deposited under ATCC Accession No. PTA-122133. Also disclosed are plants, or parts thereof, grown from the seed of the variety, plants having the morphological and physiological characteristics of the 09AY403123-1 variety, and methods of using the plant or parts thereof in a soybean breeding program.