Purpose This study aims to apply legitimacy theory and self-identity theory to the online food delivery (OFD) app service and then to investigate the impact of green brand legitimacy and biospheric value orientation perceived by customers on eco-friendly behavior.

Design/methodology/approach This study focuses on the mediating role of trust in green brands and its perceived benefits (including psychological and environmental benefits). This study involved an online survey of 445 customers who had experienced using OFD services in the past six months.

Findings The platform's green brand legitimacy and consumer perceived biospheric value orientation positively impact trust in green brands. Trust in green products and services significantly affects customers' perceived benefits and has a positive impact on eco-friendly service using behavior. Mediating effect analysis indicated that brand legitimacy and biospheric value have a positive indirect influence on the psychological benefits of supporting green activities and utilitarian environmental benefits.

Research limitations/implications The convenience sampling method is used, and its purely quantitative nature may limit the generalization of the research results.

Practical implications The OFD platform should encourage online catering retailers to use more eco-friendly packages for packaging food and minimize the provision of disposable tableware. The platform manager can provide consumers with knowledge and information on lowering related environmental pollution sources when ordering food.

Originality/value This study innovatively introduces brand legitimacy into the green consumption literature. This is an essential expansion of the content of brand legitimacy and a supplement for the research field of eco-friendly behavior.