Objective <p>Motor stereotypies (MS), emotional dysregulation (ED), and altered sensory reactivity (SENS) are highly prevalent in children with autism spectrum disorder (ASD). Various studies suggest a relationship among these variables. This study aimed to examine the relationship between ED and sensory patterns and to analyse their combined influence on MS in adolescents and adults with ASD.</p> Methods <p>In total, 97 adolescents and adults with ASD were evaluated using the Stereotyped Behavior Scale, the Emotion Dysregulation Inventory, and the Adolescent/Adult Sensory Profile. Correlation coefficients and multiple linear regression models were used to analyse the data.</p> Results <p>In the multivariate analysis, age, sensory hyporeactivity, and sensory seeking together with ED, explained MS frequency. Conversely, sensory hypo- and hiperreactivity, and ED explained MS severity. ED was correlated with both sensory hypo-/hyperreactivity, but not with sensory seeking. This relationship influenced the effect of ED on MS frequency and severity in regression models both with and without sensory variables. Intellectual disability did not demonstrate a significant influence on MS. The presence of psychopathological comorbidity had a partial influence—greater than that of ED—on MS severity.</p> Conclusion <p>The relationship between MS, ED, and SENS persists in adolescents and adults with ASD, varying according to the sensory patterns analysed. These findings support the importance of studying each pattern separately. The relationship between ED and sensory hypo-/hyperreactivity modulates the effect of ED on MS. Age and psychopathological comorbidity also influenced the results. The factors influencing the frequency and severity of motor stereotypies diverge. These results could improve our comprehension of MS, thereby facilitating more appropriate MS treatment strategies.</p>