Cottonseed products are a valuable secondary revenue source for cotton (Gossypium hirsutum L.) producers, but how production practices impact cottonseed composition is unclear. This research evaluated the effect on cottonseed composition by varying irrigation and nitrogen (N) fertilization regimes. Four cotton cultivars were grown from 2010 through 2012 under irrigated or dryland conditions and given a fertilizer application of 0 kg N ha-1, 56 kg N ha-1, or 112 kg N ha-1. Ginned seed from the plots were dehulled, and the kernels were analyzed for protein, crude oil, gossypol, soluble carbohydrates, and the oil’s fatty acid distribution. Few cultivar interactions with either irrigation or fertilization were detected. Irrigation increased kernel gossypol (18%) and oil (8%) levels but decreased kernel protein levels (13%). In contrast, the highest rate of N fertilization increased kernel protein concentration (18%) but decreased gossypol (14%), oil (9%), and soluble carbohydrate (3%) levels compared to seed kernels grown without fertilizer. In addition, N fertilization shifted the distribution of the oil’s unsaturated fatty acids toward more oleic acid and less linoleic acid. Practices growers implement to optimize lint production alter some desirable and some less desirable seed compositional traits.