Around the world, cities are creating local climate change mitigation strategies and combining strengths in international efforts. In addition to making the strategies, it is important to follow, how they work in practice. The aim of the study is to examine, how climate change mitigation policies and other events affected the consumption-based household carbon footprints in the Helsinki Metropolitan Area (HMA) from 2006 until 2012. The cities of the HMA launched an ambitious climate change mitigation strategy in 2007. Furthermore, the study analyses the changes in the carbon footprints of six different types of urban zone within the HMA: the central pedestrian zone, the fringe of the central pedestrian zone, intensive public transport zone, public transport zone, car zone and the pedestrian zones of subcentres. The results of the study reveal that the average carbon footprint decreased 7% from 2006 to 2012, despite 1% increase in expenditure, which is encouraging. Emissions caused by housing energy consumption and motor fuel consumption decreased the most. Among the urban zones, public transport zone and car zone, which are the two outermost zones of the HMA, had the strongest emission reductions. Cleaner electricity and the improved energy efficiency of buildings had a strong effect. The regression analysis of the study suggests that the central pedestrian zone and the car zone, the two most affluent zones of the HMA, have higher carbon footprints than all the other zones have between them. However, this is only true when income is controlled, not when expenditure is controlled. The economic crisis in 2008, and changes in consumption behaviour because of it, seem to explain the result. The reduction of the average carbon footprint in the HMA was not only due to steered mitigation actions. Increased housing costs seem to have contributed to the decline of consumption-based emissions. The results of the study suggest that to achieve the ambitious international, national and local climate change mitigation targets, stronger measures are needed.