Herein, we report a mild, efficient photocatalytic protocol for 1,2-carbosulfenylation of alkenes using N-hydroxyphthalimide esters as carbon sources and alkyl thiosulfate salts as sulfur sources. This operationally simple methodology provides a novel avenue for synthesizing dialkylthioether, including methylthioether, derivatives. The reaction has a broad substrate scope and excellent functional group tolerance. Mechanistic studies have elucidated the mechanism and confirmed the preferential participation of alkyl radicals in the reaction, producing the highly regioselective 1,2-carbosulfenylation of alkenes.