Greece recorded a significant decline in CO2 emissions from energy use from 2003 to 2013, accompanied by a reduction in energy consumption, particularly during the economic recession. This study attempts to identify the driving forces of CO2 emissions related to energy consumption, through the use of the complete decomposition technique developed by JW Sun. The decomposition analysis focuses on the four factors responsible for CO2 emissions: the carbon intensity effect, the energy intensity effect, the structural effect, and the economic activity effect. The analysis covers all the major productive sectors of the Greek economy. The study covers the period 2003–2013 and is divided into two subperiods (2003–2008 and 2008–2013), in order to assess changes in the contribution of the examined factors during the economic crisis (2008–2013). The analysis is extended to examine the decoupling relationship between CO2 emissions and economic growth in Greece with the use of the decoupling index.