NASA qualified the Omega Speedmaster for spaceflight in 1965.
NASA tested several commercially available chronographs for use by astronauts. The Speedmaster passed the agency’s demanding trials, which included extreme temperature changes, shocks, vibration and decompression. NASA then selected it for manned missions in March 1965.
The qualification preceded the watch’s famous lunar association. Wally Schirra had already worn a Speedmaster during the 1962 Mercury-Atlas 8 mission, but NASA’s official qualification came in 1965. Buzz Aldrin wore a Speedmaster on the lunar surface during Apollo 11 in 1969; Neil Armstrong left his inside the lunar module because the module’s electronic timer had failed.
The Speedmaster’s space qualification is distinct from Omega’s later “Moonwatch” branding. The core reason for its selection was performance in testing, not a special watch designed exclusively for NASA.