The road to Griner’s release involved "painstaking and intense negotiations," President Biden said as he thanked many across his administration who "worked tirelessly to secure her release."

"She's relieved to finally be heading home and the fact remains that she's lost months of her life, experienced a needless trauma," he said. "She deserves space, privacy and time with her loved ones to recover and heal from her time being wrongfully detained."

Biden said Griner landed in the United Arab Emirates and that the country helped facilitate the transfer.

Paul Whelan was not part of this exchange, the president said, adding, "This was not a choice of which American to bring home."

"Sadly, for totally illegitimate reasons, Russia is treating Paul's case differently than Brittney's. And while we have not yet succeeded in securing Paul's release, we are not giving up. We will never give up," Biden said. "We remain in close touch with Paul's family -- the Whelan family -- and my thoughts and prayers are with them today.

"They have to have such mixed emotions today," he continued. "And we’ll keep negotiating in good faith for Paul Whelan. I guarantee that. I say that to the family. And I guarantee you. I urge Russia to do the same to ensure that Paul's health and humane treat are maintained until we can bring him home. I don't want American to be detained one extra day if we can bring that person home."

-ABC News' Justin Gomez

Secretary of State Antony Blinken said he’s grateful to everyone “who worked tirelessly” to bring Brittney Griner home, but lamented that Paul Whelan and his family “continue to suffer needlessly.”

“Despite our ceaseless efforts, the Russian Government has not yet been willing to bring a long overdue end to his wrongful detention. I wholeheartedly wish we could have brought Paul home today on the same plane with Brittney,” he said in a statement. “We will not relent in our efforts to bring Paul and all other U.S. nationals held hostage or wrongfully detained abroad home to their loved ones.”

-ABC News’ Shannon Crawford

President Joe Biden confirmed that WNBA star Brittney Griner is on her way back to the U.S. and will be back within 24 hours.

The president said she's in "good spirits."

"She's safe. She's on a plane. She's on her way home,” Biden said.

“After months of being unjustly detained in Russia held under intolerable circumstances, Brittany will soon be back in the arms of her loved ones and -- and she should have been there all along," he said.

A senior U.S. official told ABC News that Biden signed off on the prisoner swap last week.

-ABC News' Justin Fishel and Justin Gomez

The brother of Paul Whelan, an ex-U.S. Marine currently being held in Russian prison, said they were told beforehand he would not be included in the swap and were "able to mentally prepare for what is now a public disappointment for us."

"At some level, our family has steeled ourselves for this likelihood," Whelan's brother, David, wrote in a statement. "And I think, as the use of wrongful detentions and hostage diplomacy continues around the globe, it's clear the US government needs to be more assertive. If bad actors like Russia are going to grab innocent Americans, the US needs a swifter, more direct response, and to be prepared in advance."

"In Russia's case, this may mean taking more law-breaking, Kremlin-connected Russians into custody," he added. "It's not like there aren't plenty around the world."

David Whelan also made sure to note he and his family were happy Griner has been released and said he knew the cases "were not intertwined."

"There is no greater success than for a wrongful detainee to be freed and for them to go home," he wrote. "The Biden Administration made the right decision to bring Ms. Griner home, and to make the deal that was possible, rather than waiting for one that wasn't going to happen."

The Whelan family issued a similar statement in April when U.S. citizen Trevor Reed was freed from Russia in a prisoner swap. David Whelan alluded to that in his statement Thursday, saying, "The sentiments I shared in April about Trevor are unchanged: this is the event we wish for so much for our own family. She will be reunited with her family. Brittney is free. And Paul is still a hostage."

-ABC News' Cindy Smith