Introduction Autism spectrum disorder (ASD) is a neurological and developmental disorder, which poses challenges to social communication and behavior, particularly affecting social functioning. Individuals with ASD face significant social challenges, including difficulty understanding social cues and body language, limited ability to engage in reciprocal social interactions, and challenges with establishing empathy. A preference for routines and repetitive behaviors limits their ability to adapt to new or unexpected social situations. These problems tend to escalate during adolescence. These often cause distress to the individual as well as the caregivers. Group-based social skills interventions (GSSIs) are a widely used and effective modality for addressing core social impairments in children with autism. This study aims to assess the impact of GSSI on the broad age group of eight to 15 years, involving parents to enhance the transferability of children's social skills. Methods This was a single-arm interventional study where 30 verbal autistic children, aged eight to 15 years, with intelligence quotient (IQ) > 70 were enrolled after utilizing the Binet Kamat Test of Intelligence (BKT) to assess IQ and the Indian Scale for Assessment of Autism (ISAA) to grade severity of autism. The children received GSSI from interdisciplinary therapists for 12 sessions, on a weekly basis, lasting 90 minutes each for a period of three months. After each therapy session, parents received summaries of each session and were delegated reinforcing homework assignments to enable generalization and maintenance of the skills taught. Outcome measures were taken at three points in time by utilizing the Social Communication Questionnaire (SCQ) and the parent-rated Social Responsiveness Scale 2 (p-SRS-2) T1 pre-therapy at the time of enrolment; T2 immediately post-therapy at the end of three months of training; and T3 long-term follow-up, three months after the end of training. Results Mean SCQ scores were as follows T1 = 21.87, T2 = 18.57, and T3 = 18.57 (p = 0.000). This progressive decline at T1, T2, and T3 indicated a decreasing trend in the severity of difficulties in the social communication domain. Mean p-SRS-2 scores were as follows T1 = 73.00, T2 = 64.57, and T3 = 64.30 (p < 0.0001). This declining trend at T1, T2, and T3 suggested a statistically significant decrease in the severity of difficulties faced in various social aspects tested by the p-SRS-2, i.e., social awareness, social cognition, social communication, and social motivation, along with a reduction in restricted interests and repetitive behaviors (RRBs). Very strong correlation coefficients were obtained for SCQ scores (T1-T2 = 0.921, T1-T3 = 0.921, and T2-T3 = 1.000), as well as for p-SRS-2 scores (T1-T2 = 0.743, T1-T3 = 0.746, and T2-T3 = 0.989), which reinforced the statistical significance of the data. Conclusion GSSI is an effective parent-assisted intervention for adolescents with ASD, with effects lasting up to three months post-intervention.