This study analyzes the changes of correlation between donor characteristics and Official Development Assistance in the mitigation sector (mitigation ODA) before and after the 2009 Copenhagen Accord under the United Nations Framework Convention on Climate Change. The study used multiple regression analysis using panel data of 23 countries over 15 years. The results give evidence that compared with a donor country with the poorest commitment to climate change, donor countries with a stronger commitment to climate change provided a smaller share of mitigation ODA before 2009 and vice versa after that. Furthermore, donor countries with larger GDP per capita and fewer CO2 emissions per capita provided a larger share of mitigation ODA after 2010, compared to before. These findings indicate that the Accord may have induced donors with stronger commitments to climate change, larger GDP per capita, and fewer CO2 emission per capita to contribute a larger share of mitigation ODA.