Abstract: Eyeball seals for a gimbaled rocket engines, and associated systems and methods are disclosed. A system in accordance with a particular embodiment includes a rocket body, an engine carried by and movable relative to the rocket body, and a seal assembly. The seal assembly can include a sealing surface carried by one of the rocket body and the engine, and a seal element carried by the other of the rocket body and the engine. The seal element is in contact with the sealing surface. The seal assembly can further include a cylinder and a piston slideably received in the cylinder, with one of the piston and the cylinder carrying the seal element. The cylinder includes ports that are in fluid communication with a region external to the rocket body. Accordingly, pressures external to the rocket body can force the seal element and/or the sealing surface into contact with each other.