Leveraging blockchain and Web3 technologies, Regenerative Finance (ReFi) is dedicated to advancing the financing of climate initiatives. A key innovation within ReFi is the tokenization of carbon credits. Consequently, this study explores the return connectedness among ReFi, carbon, fossil energy, and clean energy markets, employing a quantile time–frequency connectedness framework. Our findings indicate a relatively weak and time-varying trend in return connectedness. Notably, the pairwise connectedness within the ReFi-carbon-energy system becomes more pronounced during extreme market conditions compared to normal conditions. Moreover, clean energy markets of all sub-sectors serve as net spillover transmitters across different quantiles and time–frequency domains. In contrast, ReFi markets act as net receivers in the short term but evolve into net transmitters in the medium term, especially under extreme market conditions. Next, we examine the impacts of determinants on total connectedness, which demonstrate heterogeneity across different time horizons and market conditions. Finally, we confirm the usefulness of ReFi assets as effective diversification and hedging tools for carbon-energy portfolios. Our findings not only provide guidance for ReFi investors in constructing more cost-effective investment strategies, but also assist ReFi policymakers in cultivating a broader and trustworthier application of ReFi.