The power sector represents a large share of global greenhouse gas (GHG) emissions. Policy-makers have implemented a variety of instruments to decarbonise their power sector. This paper examines the Carbon Price Floor (CPF), a novel carbon pricing instrument implemented in the United Kingdom in 2013. After describing the potential mechanisms behind the recent UK power sector decarbonisation, I apply the synthetic control method on country-level data to estimate the impact of the CPF on per capita emissions. I discuss the importance of potential confounders and the amount of net electricity imports imputable to the policy. Depending on the specication, the abatement associated with the introduction of the CPF range from 104 to 156 millions tons of equivalent CO2 over the 2013-2017 period. This implies a reduction of between 39% and 48% of total power sector emissions by 2017. Several placebo tests suggest that these estimates capture a causal impact. This paper shows that a carbon levy on high- emitting inputs used for electricity generation can lead to successful decarbonisation.