This study investigates consumer willingness to substitute high-emissions meat products with lower-emissions protein products, including blends of meat and vegetables. Survey data, including a choice experiment, are combined with data on the respondents’ actual purchase behaviour. The traffic light carbon label has an effect on choice behaviour, as it increases the willingness to purchase lower-emissions protein products such as chicken and meat substitutes. We further find that the willingness to purchase these lower-emissions products is largest among individuals who are already purchasing most sustainably. We discuss policy implications from the expected impacts of carbon labels, and how such labels affect different types of consumers.