While social innovation has traditionally emphasised social sustainability, it also presents potential for the mitigation of climate change by influencing social practices. This study explores how social innovation initiatives address social practices to mitigate climate change. Our qualitative study in an affluent setting, a Swedish municipality with high emissions, led to the identification of four dimensions relevant for climate mitigation: SIIs’ social motives, inspiration of others, beneficiary participation, and use of artefacts. Social motives for climate relevant social ends focused on altering the meaning of practices while SIIs’ had social means focused on changing meaning, competences, and materials of emission-intensive practices.