This study used data from a national birth cohort study to investigate the duration of internet use at the age of 12 years among children diagnosed with attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), intellectual disabilities (IDs) and learning disabilities (LDs) at the age of five and a half years (66 months) to understand whether an ADHD, ASD, ID and LD diagnosis in childhood increases the risk of problematic internet use (PIU) in adolescence. Furthermore, the pathway relationship of dissociative absorptive trait with PIU and these diagnoses was also investigated. The 5.5- and 12-year-old Taiwan Birth Cohort Study dataset was used (N = 17,694). More boys were diagnosed with LDs, IDs, ADHD and ASD; however, girls were at increased likelihood of PIU. ID and ASD diagnoses were not associated with increasing PIU likelihood. However, children who had been diagnosed with LDs and ADHD, along with higher dissociative absorptive trait, had an indirectly increased likelihood of PIU in adolescence. Dissociative absorption was found to be a mediating factor between childhood diagnosis and PIU and can be used as a screening indicator in prevention programs to reduce the duration and severity of PIU in children diagnosed with ADHD and LDs. Furthermore, with the increased prevalence of smartphone usage in adolescents, education policy-makers should pay greater attention to the issue of PIU in female adolescents.