This study presents a systematic review of on-demand services within a sustainability context. We conducted a comprehensive weighted synthesis and a preliminary meta-analysis of 31 quantitative studies published between 2015 and 2025. Guided by a review protocol, we assess the key determinants of user adoption and behavioral intentions and identify the principal drivers of the sharing economy. The findings show that sustainability plays a crucial role in shaping consumer attitudes and intentions. Core predictors of on-demand service adoption include attitude, economic benefits, and social impact. Although economic benefits and convenience remain the primary drivers of adoption, rising awareness of environmental and social responsibility is gradually influencing consumer choices. In addition, trust and perceived risk affect user intentions, underscoring the need for platforms to strengthen transparency and security. Building on these insights, the article proposes an integrative framework that can serve as a theoretical foundation for future research. Given current limitations in the literature, future work should broaden data sources and database coverage, employ multi-method validation, conduct cross-industry comparisons, and examine workers'rights and career development to generate more explanatory and actionable insights.