Abstract: The invention relates to bifunctional stapled or stitched peptides comprising a targeting domain, a linker moiety, and an effector domain, that can be used to tether, or to bring into close proximity, at least two cellular entities (e.g., proteins). Certain aspects relate to bifunctional stapled or stitched peptides that bind to an effector biomolecule through the effector domain and bind to a target biomolecule through the targeting domain. Polypeptides and/or polypeptide complexes that are tethered by the bifunctional stapled or stitched peptides of the invention, where the effector polypeptide bound to the effector domain of the bifunctional stapled or stitched peptide modifies or alters the target polypeptide bound to the targeting domain of the bifunctional peptide. Uses of the inventive bifunctional stapled or stitched peptides including methods for treatment of disease (e.g., cancer, inflammatory diseases) are also provided.