This study investigated co-morbidity of problem gambling and problematic Internet use (PIU) among adolescent Internet and land-based gamblers, with the classic approach using sum-scores of symptoms and a promising new method, namely the network perspective. This perspective allows testing for how multiple disorders are associated, showing symptoms overlap and centralities. We used cross-sectional data from two population-based samples of adolescents aged 17 years in France (n = 2,240) and Switzerland (n = 944). Measures included Internet gambling, problem gambling and PIU. The classic approach showed that Internet gambling was associated with increased levels of disordered gambling and PIU, but that correlations between disorders were weak (R2 min = 3.2%, R2 max = 17.6%). The network perspective showed that the co-morbid network of Internet gamblers was more connected in comparison with land-based gamblers. Problem gambling and PIU appeared as separate disorders, but their relationship was increased among Internet gamblers in comparison with land-based gamblers. The network perspective appeared as a promising avenue for a better understanding of addictive disorders, but it should not replace the classic approach, which showed increased levels of addictive behaviours among Internet gamblers.