Abstract: Sustainable and biodegradable materials that are easily synthesized and fully compatible with biological systems are of great interest in manufacturing, green chemistry, and biomedical applications. Among these, peptides hold considerable promise owing to their intrinsic biocompatibility and biodegradability. Previous studies have explored non-canonical peptides and tripeptide glass structures with adhesive and self-healing properties. However, the fundamental mechanism of driving peptide adhesion remains elusive. In this work, we used six dipeptide sequences containing aromatic and charged amino acid residues. The sequences were selected based on the hypothesis that cation-π interactions facilitate strong, non-directional interactions. Remarkably, the selected sequences exhibit humidity-responsive behavior; upon exposure to high humidity, the solid dipeptide transitions to a liquid-like adhesive state that adheres to glass and metal surfaces, and upon drying, it adopts a glassy state. To quantify adhesion, we performed shear stress on stainless steel substrates. On the macro scale, the best-performing dipeptide withstood a shear stress of 33 psi, which is lower than that of conventional metal adhesives, such as epoxy (6000 to 8000 psi). However, at the nanoscale, Atomic Force Microscope (AFM) measurements revealed tensile strength up to 2100 psi, surpassing Elmer’s school glue (600 psi) and comparable polyurethanes (2000-3000 psi). Notably, these dipeptides are reversible glues since they recover their adhesive properties through multiple hydration-drying cycles due to a reversible hydrogen-bonding network. Dynamic Scanning Calorimetry (DSC) confirmed that these dipeptides exhibit a measurable glass transition temperature, typically below 80 °C in most cases. This study highlights the potential of simple, short, and tunable peptides as fully biodegradable, environmentally friendly alternatives to conventional adhesives and glassy materials.