Abstract: Since the Industrial Revolution, the global average surface temperature has increased by approximately 1.1 °C. As a result, the frequency and intensity of events such as extreme heat, heavy precipitation, glacier retreat, and sea-level rise have increased significantly. The Sixth Assessment Report of the Intergovernmental Panel on Climate Change clearly states that the main driving forces behind this warming trend is the continuous increase in carbon dioxide (CO₂) emissions caused by human activities and its concentration in the atmosphere. Currently, atmospheric CO₂ concentration exceeds 420×10^–6 g∙cm^–3 which is over 50% higher than the pre-industrial level, and the annual increase is 2×10^–6 ‒ 3×10^–6 g∙cm^–3. Systematically mastering high-precision and multiscale observation methods for atmospheric CO₂ concentrations and fluxes is a technical means to understand the carbon cycle mechanism of the Earth’s system and a scientific basis for evaluating the potential of natural and anthropogenic carbon sinks. It is also a key support for the international community to assess the effectiveness of emission reduction, formulate emission reduction policies, and satisfy the temperature control goals of the Paris Agreement to implement China's carbon peak and carbon neutrality strategy. Constructing a high-precision, multiscale, and comprehensive atmospheric carbon observation technology system has become one of the most urgent scientific tasks to address global climate change. This paper reviews the latest advances in atmospheric CO₂ observation technologies and their data applications. First, it systematically organizes the three types of technical systems for carbon concentration observations: ground-based, airborne, and space-based. For ground-based observations, this study focuses on introducing two ground observation techniques: sampling analysis and continuous online automatic monitoring, as well as relevant information on carbon data products from major ground-based CO₂ concentration observation networks. For airborne observations, the methods and characteristics of aircraft surveys and unmanned aerial vehicle detections are summarized. For space-based observations, the accuracy and spatial resolution of column-averaged concentration products from satellites such as GOSAT, OCO–2/3, and TanSat are compared. In terms of flux observations, this study compares and summarizes the advantages, disadvantages, and application scenarios of “bottom-up” methods, including the chamber, eddy covariance, flux gradient, profile, and eddy accumulation methods. It also introduces “top-down” methods, such as carbon assimilation and atmospheric inversion methods, as well as atmospheric chemical transport models at different scales, clarifying the principles and characteristics of each technique. Finally, this study aggregates the carbon concentration and carbon flux databases established based on carbon information obtained through carbon observation technologies, introduces the importance of these technologies in the estimation of carbon sources/sinks, and the applications and prospects of different carbon neutrality scenario simulation models. Suggestions are put forward on the future development direction of carbon observation technologies; in particular, to construct a “space-air-ground” three-dimensional monitoring network through the integration of “multiscale and multimethod” approaches to provide ideas and solutions for the construction of a joint carbon observation technology system in China and the world. In conclusion, this review systematically organizes atmospheric CO₂ observation technology systems and application paths, providing reference and support for the research and development of global carbon observation technologies and China's efforts to address climate change and achieve carbon peak and carbon neutrality goals.