Vostok 1 was the first spacecraft to carry a human, Yuri A. Gagarin, into space, occurring 25 days prior to the first U.S. suborbital flight. Due to concerns about adverse reactions to weightlessness, the manual controls on the spacecraft were locked prior to launch, and the entire flight was under the control of ground personnel.

The spacecraft consisted of a nearly spherical cabin covered with ablative material. It featured three small portholes and external radio antennas. Inside the manned cabin were radios, a life support system, instrumentation, and an ejection seat. This cabin was attached to a service module that carried chemical batteries, orientation rockets, the main retro system, and additional support equipment for the total system. This module was separated from the manned cabin during reentry.

After one orbit, the spacecraft reentered the atmosphere and landed in Kazakhstan (about 26 km southwest of Engels) 1 hour and 48 minutes after launch. The Vostok spacecraft was designed to eject the cosmonaut at approximately 7 km, allowing him to return to Earth by parachute. Although initial reports were unclear about whether Gagarin landed this way or returned in the spacecraft, subsequent reports confirmed that he did indeed eject from the capsule. Radio communications with Earth were continuous during the flight, and television transmissions were also made from space.