Surrogate decision makers (SDMs) of the critically ill experience intense emotions and transient states of decision fatigue. These factors may increase the cognitive load experienced by electronic decision aids. This cross-sectional study explored the associations of emotion regulation (expressive suppression and cognitive reappraisal) and decision fatigue with cognitive load (intrinsic and extraneous) among a sample of 97 SDMs of the critically ill. After completing subjective measures of emotion regulation and decision fatigue, participants were exposed to an electronic decision aid and completed a subjective measurement of cognitive load. Multiple regression analyses indicated that decision fatigue predicted intrinsic cognitive load and expressive suppression predicted extraneous cognitive load. Emotion regulation and decision fatigue represent modifiable determinants of cognitive load among SDMs exposed to electronic decision aids.