Oceanic submesoscale processes (submesoscales) — encompassing vortices, fronts, and filaments on horizontal scales of O(1–30) km — strongly influence the ocean's kinetic energy (KE) and heat budgets, thereby greatly regulating the Earth's climate system. Our review synthesizes the key advances in submesoscale physics, focusing on their dynamical impacts. We show that submesoscales can be generated through different mechanisms, such as baroclinic instability, frontogenesis, and current-topography interactions, which lead to enhanced submesoscale activity in regions with strong current and complex topography and winter intensification in the upper ocean. Submesoscales drive a bi-directional KE transfer: upscale to reinforce mesoscale processes and downscale to enhance turbulent dissipation, which greatly regulates the ocean's KE reservoir. Equally vital is their substantial capacity for vertical and horizontal tracer transport, critically modulating budgets of heat, carbon, and other tracers in the global ocean. Through these processes, submesoscales affect air–sea interactions and larger-scale ocean dynamics and climate, such as enhancing or dissipating mesoscale processes, weakening the amplitude of El Niño/Southern Oscillation, and modulating mode waters' formation and the Meridional Overturning Circulation. Moving forward, coordinated efforts that integrate ultra-high-resolution observations and simulations are essential to accurately quantify submesoscales’ roles in global KE and tracer budgets and better understand their broader climate impacts.