The twice Olympic champion pleaded guilty to the charges of possessing and smuggling illegal drugs but insisted she had made an "honest mistake". In November she was moved to a penal colony in Russia.
"My best friend is on the way Home!!!!! I love you BG!!!" Emma Cannon (33), who plays for the Indiana Fever and was previously on Griner's Phoenix Mercury, wrote on Twitter.
"Thank you to every single person that kept Brittney Griner’s name alive," her Phoenix Mercury teammate Brianna Turner (26) tweeted.
The WNBA and its men's counterpart, the National Basketball Association (NBA), had advocated for the release of the eight-times All-Star.
"BG is FREE!!! 294 days and she is coming home!!!" tweeted twice WNBA champion and finals MVP Breanna Stewart of the Seattle Storm, who was among the league's vocal advocates for her release.
The Russian foreign ministry said on Thursday it traded Griner for Russian former arms dealer Viktor Bout.
