Abscisic acid (ABA) was chemically modified with a photocaging group to promote photo-induced protein dimerization. This photo-controlled chemically induced dimerization (CID) method based on caged ABA enables dose-dependent light regulation of cellular processes, including transcription, protein translocation, signal transduction and cytoskeletal remodeling, without the need to perform extensive protein engineering. Caged-ABA can be easily modified to respond to different wavelengths of light. Consequently, this strategy should be applicable to the design of light-regulated protein dimerization systems and potentially be used orthogonally with other light-controlled CID systems.