Children who survive a brain tumor diagnosis often suffer from emotional difficulties that decrease their quality of life. We monitored eye-movements during the control of attention to emotional faces to measure emotion regulation. Brain tumor survivors had difficulty regulating their initial attention away from emotional faces, and those who exhibited poor emotion regulation displayed the least emotional control in daily life. White matter of the splenium of the corpus callosum predicted emotion regulation. Our findings may improve the identification of children at risk for poor functional outcomes, and suggest the splenium as a candidate neuroanatomic substrate of emotion regulation.