The school colors for University of Delaware are blue and yellow-gold. The faculty of Delaware College first chose blue and gold as the college colors in 1889. This decision may have come in connection with the development of team sports, for this same fall was the first football season. The colors adopted were those of the state of Delaware. The Delaware state flag, officially adopted in 1913, has a buff-colored diamond with the coat of arms, surrounded by a background of colonial blue. According to the original designers of the flag, the shades of buff and colonial blue represent the colors of General George Washington's uniform. Blue and gold are also the colors of Sweden, from which Delaware's first permanent colonists came.

For the football helmet only, a metallic blue is used instead of the standard blue. Metallic gold can be substituted for yellow in some cases.