AbstractBoronic acids (BAs) are a promising bioconjugation function to design dynamic materials as they can establish reversible covalent bonds with oxygen/nitrogen nucleophiles that respond to different pH, ROS, carbohydrates and glutathione levels. However, the dynamic nature of these bonds also limits the control over the stability and site‐selectivity of the bioconjugation, which ultimately leads to heterogeneous conjugates with poor stability under physiological conditions. Here we disclose a new strategy to install BAs on peptide chains. In this study, a “boron hot spot“ based on the 3‐hydroxyquinolin‐2(1H)‐one scaffold was developed and upon installation on a peptide N‐terminal cysteine, enables the site‐selective formation of iminoboronates with 2‐formyl‐phenyl boronic acids (Ka of 58128±2 m−1). The reaction is selective in the presence of competing lysine ϵ‐amino groups, and the resulting iminoboronates, displayed improved stability in buffers solutions and a cleavable profile in the presence of glutathione. Once developed, the methodology was used to prepare cleavable fluorescent conjugates with a laminin fragment, which enabled the validation of the 67LR receptor as a target to deliver cargo to cancer HT29 cells.