We conducted a systematic review of the literature to evaluate the quality of the dietary data and the methods used to obtain them in studies with children and adolescents with ASD. The search of PsycINFO, PubMed, SciELO, and Web of Science using SPIDER strategy retrieved 1975 studies. Data on dietary intake assessment methodologies were extracted. Eighty-nine studies were included. Food records and food frequency questionnaires were the most frequent dietary assessment methods. Overall, studies presented a low quality score. Most of them did not report dietary assessment of bias, description of dietary method application, validity, sensitivity analyses, and statistical adjustments. Future studies must improve the application of dietary assessment methods to advance scientific evidence related to nutrition in ASD.