From Tourism Intermediary Leverage to Sustainable Development Outcomes: A Systematic Review of Tour Operators, Travel Agencies and Platforms

Tourism intermediaries are expected to contribute to sustainable development, yet research often stops at policies, intentions or reported practices. This review examines how far studies trace intermediary influence from organisational leverage and action to adoption by another actor and to sustainable outcomes. The corpus includes 113 Scopus and Web of Science reports published between 1997 and July 2026. The review was not prospectively registered. Design‐specific appraisal produced 20 higher, 41 moderate and 52 lower confidence ratings. Evidence is concentrated on tour operators and travel agencies; platforms and destination‐level effects remain underexamined. Orchestration appeared in 59 reports (52.2%), while translation and selection each appeared in 48 (42.5%). Most reports (97/113; 85.8%) stopped at or before intermediary action, whereas only 16 (14.2%) followed the chain to another actor's response or a measured sustainability outcome. The framework clarifies where evidence weakens and what future research should observe directly.