This study investigates the tunable instability in suspended monolayer two-dimensional (2D) materials, such as graphene and MoS₂, using a push-to-shear (PTS) strategy. The research quantitatively examines the dynamic wrinkling-splitting-smoothing process, revealing stepwise instabilities governed by material geometry, pretension, and elastic nonlinearity. The instability and recovery paths are attributed to local stress redistribution in the materials. The findings demonstrate that the bending stiffness of monolayer 2D materials can be measured, and the instability patterns can be programmed for nanoscale applications. The study highlights the importance of understanding instability in suspended 2D materials due to their unique mechanical and physical properties. The research addresses the challenge of controlling instability in suspended 2D materials, which is crucial for applications in micro/nanoelectromechanical systems (M/NEMS), nanochannels, and proton transport membranes. The team employed in situ shear loading-unloading experiments to observe the instability behavior, revealing primary and secondary instabilities. The primary instability is reversible, while the secondary instability involves stepwise wrinkle splitting, which is distinct from the recovery process. The study also establishes a scaling law relating bending stiffness, Young's modulus, strains, and wrinkling wavelength, enabling the measurement of bending stiffness. The results show that the bending stiffness of monolayer graphene and MoS₂ is approximately 3–20 eV and 25–35 eV, respectively. The research further explains the different instability and recovery trajectories through local stress redistribution in the materials. The findings contribute to the understanding of instability in 2D materials and provide insights for future applications in nanoscale devices and electronics.This study investigates the tunable instability in suspended monolayer two-dimensional (2D) materials, such as graphene and MoS₂, using a push-to-shear (PTS) strategy. The research quantitatively examines the dynamic wrinkling-splitting-smoothing process, revealing stepwise instabilities governed by material geometry, pretension, and elastic nonlinearity. The instability and recovery paths are attributed to local stress redistribution in the materials. The findings demonstrate that the bending stiffness of monolayer 2D materials can be measured, and the instability patterns can be programmed for nanoscale applications. The study highlights the importance of understanding instability in suspended 2D materials due to their unique mechanical and physical properties. The research addresses the challenge of controlling instability in suspended 2D materials, which is crucial for applications in micro/nanoelectromechanical systems (M/NEMS), nanochannels, and proton transport membranes. The team employed in situ shear loading-unloading experiments to observe the instability behavior, revealing primary and secondary instabilities. The primary instability is reversible, while the secondary instability involves stepwise wrinkle splitting, which is distinct from the recovery process. The study also establishes a scaling law relating bending stiffness, Young's modulus, strains, and wrinkling wavelength, enabling the measurement of bending stiffness. The results show that the bending stiffness of monolayer graphene and MoS₂ is approximately 3–20 eV and 25–35 eV, respectively. The research further explains the different instability and recovery trajectories through local stress redistribution in the materials. The findings contribute to the understanding of instability in 2D materials and provide insights for future applications in nanoscale devices and electronics.