Purpose <p>Autistic children are more likely to experience challenges with poor diet quality or selective eating behaviours in comparison to neurotypical peers, which may predispose them to nutrient deficiencies and suboptimal weight status. Thus, it is crucial to identify factors associated with these two unfavourable dietary behaviours in autistic children. This cross-sectional study examined the associations between screen time and sleep quality with diet quality and food selectivity among autistic children, and the extent to which screen time was indirectly associated with diet quality and food selectivity through sleep quality.</p> Method <p>The parents of 628 autistic children aged 7–12 years in Australia reported on their child’s screen time, sleep quality, diet quality and food selectivity via an online questionnaire.</p> Results <p>Structural equation modelling of the hypothesised mediation model revealed significant associations between screen time and sleep disturbances (β = 0.118, 95%CI = 0.032, 0.204, <i>p</i> = .007), and between sleep disturbances with lower diet quality (β = -0.077, 95%CI = -0.153, -0.001, <i>p</i> = .047) and higher food selectivity (β = 0.198, 95%CI = 0.119, <i>p</i> &lt; .001). Sleep disturbances only weakly explained the indirect association between screen time and food selectivity (β = 0.023, 95%CI = 0.004, 0.043, <i>p</i> = .018), whereas the indirect association between screen time and diet quality through sleep disturbances was non-significant (β = -0.009, 95%CI = -0.020, 0.002, <i>p</i> = .110).</p> Conclusion <p>Higher screen time and poor sleep quality emerged as significant factors associated with unfavourable dietary behaviours among autistic children.</p>