Social decision making is often challenging for autistic individuals. Twenty autistic adolescents made decisions in the socially interactive context of a one-shot ultimatum game, and performance was compared to a large matched typical reference sample. Theory of mind, executive functioning and emotion regulation were measured via direct assessments, self- and parent report. Relative to the reference sample, autistic adolescents proposed fewer fair offers, and this was associated with poorer theory of mind. Autistic adolescents responded similarly to the reference sample when making decisions about offers proposed to them, however they did not appear to down regulate their negative emotion in response to unfair treatment in the same way. Atypical processes may underpin even apparently typical decisions made by autistic adolescents.