Peptides and peptidomimetics are attractive drug candidates because of their high target specificity and low toxicity profiles. Developing peptidomimetics using hydrocarbon (HC)-stapling or other covalent stapling strategies has gained momentum because of their high stability and resistance to proteases. However, the various covalent stapling methods can also be low yielding as they require two-step synthesis and purification. The rigid nature of covalent stapling may also disrupt the network of stabilizing intramolecular interactions present in the bound state of the native peptides resulting in the stapled peptidomimetics having poor affinity for their targets. We have taken advantage of the α-methyl group and an aromatic phenyl ring in a unique unnatural amino acid, α-methyl-L-phenylalanine (αF), to generate a novel, non-covalent stapling strategy with one-step synthesis and purification to stabilize peptides. We utilized this strategy to create an α-helical B-chain mimetic of a complex insulin-like peptide, human relaxin-3 (H3 relaxin)[1]. Our comprehensive dataset (in vitro, ex vivo, and in vivo) confirmed that the new high-yielding B-chain mimetic, H3B10-27(13/17αF), is remarkably stable in serum, mimics α-helical structure of the H3 relaxin B-chain and demonstrates similar potency to H3 relaxin in vitro and in vivo targeting its G protein-coupled receptor RXFP3. More recently, we have demonstrated that this stapling method was effective for the generation of a single chain peptidomimetic of the related insulin-like peptide 5 (INSL5) which targets the RXFP4 receptor. Importantly, αF peptidomimetics of INSL5 demonstrated at least 10-fold higher affinity and potency at RXFP4 compared to similar INSL5 peptidomimetics using covalent stapling strategies. We therefore believe that our novel stapling strategy will have general utility in generating α-helical peptidomimetics for a wide range of biologically important peptide targets.