PurposeThe express delivery industry faces challenges engaging consumers in sustainable practices. This study explores how sustainable service quality affects corporate loyalty, mediated by value co-creation (VCC) and green customer satisfaction. It also scrutinizes low-carbon knowledge as a moderator and investigates variances in VCC outcomes between Generation Y and Generation Z consumer groups.Design/methodology/approachAn empirical study involves a scenario experiment and a questionnaire answered by 596 Chinese consumers in 2023. Partial least squares structural equation modeling (PLS-SEM) tests proposed relationships. Regression analysis examines the chain mediating effect of VCC and green satisfaction, while group analysis assesses intergenerational differences.FindingsSustainable service quality positively influences consumer VCC, which in turn impacts customers’ green satisfaction and corporate loyalty. VCC and green satisfaction act as intermediaries between sustainable service quality and corporate loyalty. Low-carbon knowledge positively moderates sustainable service quality's impact on VCC. Generation Y and Generation Z show differences in the relationship between VCC and loyalty.Practical implicationsExpress delivery firms should enhance sustainable service quality and encourage consumer participation in VCC activities. This can improve consumer green satisfaction, loyalty and competitive advantages.Originality/valueThis study expands service marketing literature by clarifying VCC's role in sustainable services and offers insights into VCC's causes and effects. It proposes strategies for the express delivery industry to influence consumer behavior through sustainable service practices.