© 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.This study aims to compare smartphone addiction level, temperament, and character and parental attitudes of adolescents with and without attention deficit hyperactivity disorder (ADHD). For this purpose, 143 adolescents with and without ADHD and their parents were included in the study. Participants completed the “Smartphone Addiction Scale-Short Form,” “Junior Temperament and Character Inventory,” and “Parental Attitude Research Instrument.” According to the analysis, the smartphone addiction scores of adolescents with ADHD were significantly higher than those in without ADHD group. Both groups differed in terms of temperament and character and parental attitudes. Hierarchical regression analyses revealed that high novelty seeking and low overprotection parental attitude were significantly associated with smartphone addiction scores in ADHD group, whereas high novelty seeking and low persistence were significantly associated with smartphone addiction scores in without ADHD group. This study is exceptionally important in terms of demonstrating the relationship between ADHD and smartphone addiction. Important findings related to parental attitude and temperament and character were also revealed.