Abstract: Under the context of the dual carbon goals and high-quality urban development, urban green spaces (UGS), as one of the most important natural carbon sinks in urban ecosystems, play a critical role in mitigating climate change and reducing urban carbon emissions. In recent years, research on UGS carbon sequestration has been evolving from single, static carbon stock assessments toward a comprehensive framework that integrates carbon budget, emission reduction effects, ecosystem service flows, and governance systems. This commentary discusses the theory, methods, and pathways of carbon sequestration enhancement and emission reduction in UGS development from multiple perspectives, including precise carbon accounting, life-cycle carbon budget, indirect emission reduction benefits, ecosystem service flows, and low-carbon planning and construction. The core viewpoints are summarized as follows: 1) Accurate carbon accounting is the foundation of UGS carbon sequestration relative research. Given the high heterogeneity of UGS, it is urgent to achieve a transformation from coarse estimation to dynamic and high-resolution accounting through multi-scale coordinated monitoring, integration of process-based and data-driven models, and the establishment of standardized methodological systems. 2) UGS are complex carbon metabolic systems under strong anthropogenic influence, simultaneously functioning as both carbon sources and sinks. Traditional accounting approaches focusing solely on biomass carbon sequestration tend to systematically overestimate their net carbon benefits. Therefore, localized parameter systems and standardized methodologies are necessary to dynamically characterize life-cycle carbon budget and better support the optimization of net carbon sequestration. 3) UGS provide significant indirect emission reduction benefits through multiple ecosystem services, such as mitigating urban heat island effects, improving air quality, and regulating urban stormwater processes. Future assessments should shift from single carbon sequestration evaluation to an integrated framework that combines direct carbon sequestration, life-cycle emissions, and multiple ecosystem services, thereby supporting high carbon-performance optimization of UGS. 4) Carbon sequestration and related ecosystem services of UGS exhibit strong spatial spillover effects, influencing urban carbon balance and spatial equity through ecosystem service flows. Planning at spatial scales should therefore focus on flow direction, flow magnitude, and transboundary ecological compensation mechanisms. 5) UGS are transitioning from traditional landscape spaces to low-carbon infrastructure systems. Carbon management should be integrated throughout the entire lifecycle of planning, design, construction, and maintenance, and a multi-scale, multi-process, and multi-stakeholder coordinated low-carbon green space planning and governance framework should be established.