Whole cottonseed (WCS) is commonly used in adult ruminant nutrition due to its combined fiber, energy, and protein content; however, information on its use in preweaned dairy calves remains limited. This study evaluated the effects of partial replacement of calf starter with whole cottonseed on growth performance and feed intake of preweaned Holstein calves. A total of 36 calves were randomly assigned to one of three dietary treatments: a control diet without WCS, a diet containing 10% WCS, and a diet containing 20% WCS on a dry matter basis. Calves were monitored throughout the preweaning period for body weight, average daily gain (ADG), dry matter intake (DMI), and feed efficiency. Partial replacement of calf starter with whole cottonseed did not significantly affect final body weight, ADG, DMI, or feed efficiency (p > 0.05). Growth performance was comparable among all dietary treatments. Increasing levels of whole cottonseed reduced in vitro gas production and estimated dietary energy values; however, these changes were not associated with differences in in vivo growth or feed utilization. The results indicate that whole cottonseed can be included in calf starter diets at levels up to 20% without adverse effects on preweaning growth performance. Under controlled management conditions, whole cottonseed may be considered a viable alternative feed ingredient in calf starter formulations. Further studies are warranted to evaluate long-term effects on rumen development and postweaning performance.