Parks are important public resources that offer opportunities to be physically active and connect socially. However, parks are not well attended by adolescents, and limited research exists to inform optimal park design to increase adolescents’ park visits and support active and social park use. This study aimed to gain in-depth insights into park characteristics that are important for influencing park visitation, park-based physical activity and social interaction among adolescents. Participants (n = 34, aged 13–18 years, 41.2 % female) were recruited from diverse neighbourhoods in Melbourne, Australia. Walk-along interviews were conducted in nine pre-selected parks, where researchers and participants walked together during the interview. The interviews were audio-taped, transcribed verbatim and analysed using content analysis. The most commonly mentioned characteristics for encouraging park visitation were: the presence of natural features; sports features (e.g., sports courts); playgrounds; aesthetics/condition; and location. The presence of sports features, fitness equipment, walking/cycling paths, playgrounds and green open space were the most frequently mentioned features for encouraging park-based physical activity. The most commonly mentioned features for encouraging socialising when at the park were: presence of barbecue/picnic areas; sports features; seating; organised events; and shade/shelter. Female adolescents more commonly mentioned safety and the presence of playgrounds, and males more commonly noted sports features, size and location as being important for park visitation. Adolescents also considered social factors, such as accompaniment and peer influence, as being critical for encouraging them to visit the park. Many park features were important for all behaviours. For example, sports features were most commonly mentioned as being important for encouraging adolescents’ park visitation and active and social park use. Stakeholders should consider these factors when (re)designing parks to ensure the parks appeal to this sub-population and encourage adolescents to visit and be active and social in this setting.