Parents of children with autism spectrum disorder (ASD) may have difficulty engaging their children through play, thus affecting the parent–child relationship and parental self-efficacy. This study intended to examine children’s sensory profile and adults’ playfulness as predictors of parental self-efficacy. A total of 136 parents of children ages 3–7 yr completed the Short Sensory Profile, the Playfulness Scale for Adults, and the Tool to Measure Parenting Self-Efficacy. For the parental couples of children with ASD, the most relevant predictor of general parental self-efficacy was the child’s sensory profile. However, adult playfulness resulted in the most relevant predictor of emotional parental self-efficacy. Findings suggest the importance of considering play as a relevant co-occupation that must be acknowledged when intervening with families of children with ASD and considering the child’s sensory modulation abilities, as well as parents’ playfulness and sense of self-efficacy, as potential outcomes when designing and evaluating treatment programs.