The strong, meandering, and eddy‐shedding Gulf Stream is a large oceanic reservoir of both mean and eddy kinetic energy in the northwestern Atlantic. Since 2015, underwater gliders equipped with Doppler current profilers have collected over 20,000 absolute velocity profiles in and near the Gulf Stream along the US East Coast. Those observations are used to make three‐dimensional estimates of mean and eddy kinetic energy, substantially expanding the geographic coverage of prior estimates of subsurface kinetic energy in the Gulf Stream. Glider observations are combined via weighted least squares fitting with anisotropic and inhomogeneous length scales to reflect both circulation and sampling density; this averaging technique can be applied to other quantities measured by the gliders. Mean and eddy kinetic energy decay approximately exponentially away from the surface. Vertical decay scales are longest within the high‐speed core of the Gulf Stream and somewhat shorter on the flanks of the Gulf Stream. Plain Language Summary Energy is a key metric of the Earth's climate system, of which the ocean is a major part. Kinetic energy, the energy of moving water in the ocean, is partitioned into mean kinetic energy that is associated with the time‐averaged ocean circulation and eddy kinetic energy that is associated with time‐varying motions. Here, a large set of velocity measurements collected by autonomous underwater gliders is used to make three‐dimensional estimates of mean and eddy kinetic energy in and near the Gulf Stream, one of the strongest currents in the global ocean. These new estimates of oceanic kinetic energy serve as a benchmark for numerical simulations of the ocean and climate system to reproduce. Key Points Underwater glider observations are used to produce three‐dimensional estimates of mean and eddy kinetic energy in and near the Gulf Stream Mean and eddy kinetic energy generally decay exponentially with depth and have somewhat longer decay scales within the Gulf Stream Three‐dimensional mean and eddy kinetic energy fields are available for further analyses and will be updated with future observations