In recent years, developing effective theranostic agents for precise cancer treatment has been one of the most prevalent strategies. Herein, three staurosporine derivatives, MCY‐STS, ECY‐STS, and ICY‐STS, synthesized through minor modifications of natural staurosporine, are reported. These derivatives not only exhibit attractive fluorescence properties, including solvatochromism and dual‐state (solution and solid) emission, but also demonstrate potent protein kinase C inhibitory activity and anticancer effects against NCI‐N87, MCF‐7, and SK‐OV‐3 cell lines. Theoretical calculation analyses, including density functional theory calculations, molecular docking, and molecular dynamics simulations, are employed to elucidate their protein–ligand interactions and luminescence mechanisms. Further investigations reveal that ECY‐STS significantly inhibits tumor growth while illuminating tumor tissues for therapy visualization. Collectively, these modified fluorescent staurosporine derivatives, particularly ECY‐STS, represent promising theranostic agents that provide a novel strategy for cancer imaging and treatment in humans.