Provided are: a thermally conductive composition from which a thermally conductive sheet having satisfactory thermal conductivity and flexibility can be formed; and a thermally conductive sheet produced using the thermally conductive composition. This thermally conductive composition comprises an organopolysiloxane, a thermally conductive filler, an alkoxy silane compound and a siloxane-modified acrylic resin, in which, when the content of the organopolysiloxane is defined as 100 parts by mass, the total content of the alkoxy silane compound and the siloxane-modified acrylic resin is 100 parts by mass or more. The thermally conductive sheet comprises a cured product of the thermally conductive composition.