Abstract: Hydrofunctionalization, or the addition of an X–H bond across a π-bond, is an atom-economical method to quickly introduce new functionalities and stereochemistry into molecules. We developed a novel hydroamination using Pd-catalysis, and two regiodivergent hydroselenations promoted by light or Rh. Detailed mechanistic studies reveal interesting aspects of these reactions, including a unique ligand-ligand hydrogen transfer (LLHT) hydroamination mechanism and a novel β-seleno effect. In addition to hydrofunctionalization, we also have designed and made efforts towards synthesizing a novel oncoimmunotherapeutic co-drug.