UNLABELLED: Autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) often co-occur. Developmental stages significantly influence the variations in brain alterations. However, whether ASD comorbid with ADHD (ASD + ADHD) represents a unique neural characteristic from ASD without comorbid ADHD (ASD-alone), or instead manifests a shared neural correlate associated with ASD across diverse age cohorts remain unclear. This study examined topological properties and functional connectivity (FC) patterns through resting-state functional magnetic resonance imaging data from the Autism Brain Imaging Data Exchange II. Participants were divided into two age cohorts: childhood (under 12 years) and adolescence (12-18 years), consisting of 171 ASD pediatric patients and 111 typically developing (TD) controls. These cohorts were further classified into subgroups of ASD + ADHD, ASD-alone, and TD controls to compare across the age categories. The age, intelligence quotient, and gender of participants across three groups were matched within childhood and adolescence stages. We constructed functional brain networks, conducted graph-theory analysis, and analysed FC for both age cohorts. The findings revealed that both ASD + ADHD and ASD-alone shared some FC dysfunctions in the Default Mode Network (DMN) and atypical global metrics. Additionally, each group demonstrated unique neural FC and topological profiles that evolved with development. CONCLUSIONS: This study highlights the neural profiles of ASD + ADHD from a developmental perspective and suggests age-considerate approaches in clinical treatments. WHAT IS KNOWN: • ASD + ADHD shared some neural correlate associated with ASD-alone and also had specific neurobiological mechanisms which were different from ASD-alone. • Developmental stages significantly influence the variations in brain alterations observed in ASD or ADHD. WHAT IS NEW: • Both ASD + ADHD and ASD-alone shared some FC dysfunctions in the Default Mode Network and atypical global metrics. • ASD + ADHD and ASD-alone demonstrated unique neural FC and topological profiles that evolved with development.