In addition to socioeconomic factors, urban morphology is increasingly being recognized for the potential role it might play in tackling climate change. Meanwhile, improving CO₂ emission efficiency has become a significant aim in reducing CO₂ emissions without sacrificing economic development. Hence, investigating the effects of urban landscape pattern on CO₂ emission efficiency is of great importance. As thus, this study is designed to quantitatively estimate the associations between urban landscape pattern and CO₂ emission efficiency, using panel data for five megacities in China in the period 1990–2013. A series of landscape metrics were first selected to quantify three dimensions of urban landscape pattern, namely urban expansion, urban shape complexity, and urban compactness. CO₂ emission efficiency was then evaluated using three quantitative indicators, namely per capita CO₂ emission, CO₂ emission intensity, and CO₂ emission performance. Finally, panel data models were performed to estimate the influences of urban landscape pattern on CO₂ emission efficiency. The results demonstrate that both urban expansion and urban shape complexity inhibited the improvement of CO₂ emission performance. In addition, urban compactness was found to be conducive to the reduction of CO₂ emission per capita and CO₂ emission intensity, as well as the improvement of CO₂ emission performance. The findings obtained through this study cast a new light on the significance of city planning and the optimization of spatial structure in improving CO₂ emission efficiency, providing decision makers and urban planners with a scientific basis from which to approach the task of reducing CO₂ emissions whilst maintaining economic development.