WNBA Commissioner Cathy Engelbert applauded the release of Griner, an eight-time league All Star, and said she showed "extraordinary courage and dignity in the face of enormous adversity."

"There has not been a day over the past ten months where we all haven’t had Brittney Griner on our minds and in our hearts and that has now turned into a collective wave of joy and relief knowing that she will soon be reunited with her family, the WNBA player community, and her friends," Engelbert wrote in a statement.

The WNBA celebrated Griner all season, putting her No. 42 on every court and even having every player in this year's All Star Game wear her number. Many players spoke out throughout the season for her release.

NBA Commissioner Adam Silver, who had also consistently pushed for Griner's release, said in a statement, "Brittney has had to endure an unimaginable situation and we're thrilled that she is on her way home to her family and friends. We thank the members of the NBA and WNBA community who never wavered in their efforts to raise awareness of Brittney's unjust circumstances."

Seattle Storm star Breanna Stewart, the 2018 WNBA MVP and a teammate of Griner on both the U.S. national team and Russian squad UMMC Ekaterinburg, had posted a plea for Griner's release every day on Twitter, counting the days and tagging President Joe Biden, Vice President Kamala Harris and the White House in the posts. On Thursday, she wrote, "BG is FREE!!! 294 days and she is coming home!!!"

Derek Maltz, who oversaw the Drug Enforcement Administration’s investigation of Viktor Bout, told ABC News he’s “very disgusted” that Bout, a convicted Russian arms dealer, was traded for Brittney Griner.

“It’s really upsetting to me,” he said.

In 2008, Maltz was the special agent in charge of the DEA’s special operations division whose agents took down Bout in a sting operation in Thailand.

“DEA was asked to help take this guy down because he was such a national security threat,” Maltz said.

In November 2007, Bout agreed to sell DEA informants posing as rebels in Colombia millions of dollars in weapons.

“Bout was ready to sell a weapons arsenal that would be the envy of any small country,” Maltz said.

Maltz called this “a great day for Brittney Griner and for America,” but added that he thinks the exchange for Bout will make Americans traveling abroad less safe.

“To make that exchange, all Americans are at greater risk with international travel,” Maltz said, fearing it would promote taking American citizens captive.

-ABC News’ Aaron Katersky

Brittney Griner is “in an extremely upbeat mood” and is “all smiles,” according to a senior Biden administration official.

The athlete is “in good health” and “is being offered a wide range of support options following her time wrongfully detained,” the official added.

The agreement to secure her release was reached in “recent days,” the official said.

“Through multiple, multiple engagements, the Russians made clear that the only route to securing Britney's return was a release of a Russian national, Viktor Bout,” the official said. “In the last 48 hours, as this had all come together, Brittney was moved from the penal colony where she was being held to Moscow, and this morning, she was brought to the United Arab Emirates, where she was met by U.S. officials.”

-ABC News’ Ben Gittleson

New photos released by Jill Biden's office show the first lady hugging Brittney Griner's wife, Cherelle Griner, at the White House Thursday morning.

"Brittney is coming home," the first lady wrote.