Griner, an American basketball star who has been jailed in Russia on drug charges, is exchanged for Viktor Bout, a Russian arms dealer. Bout was already in Moscow, where state television showed him hugging his wife and mother.
The US and Russia have swapped imprisoned US basketball star Brittney Griner for notorious arms dealer Viktor Bout, who was held in American prisons for 12 years.
President Joe Biden said Griner was safe and on the plane home from the United Arab Emirates.
"I'm pleased to say Brittney is in good spirits... she needs time and space to recover," he said at the White House.
Bout - widely known as the "merchant of death" - has arrived back in Moscow, Russian media report.
"In the middle of the night they woke me up and said 'Put your things in order' and that was it," Bout said in brief remarks to a reporter from national television, after landing in Russia.
Bout reportedly descended the plane steps carrying a bouquet of flowers before embracing his mother and wife.
Griner was arrested at a Moscow airport in February for possessing cannabis oil and last month was sent to a penal colony.
The Biden administration proposed a prisoner swap in July, recognizing that Moscow had long demanded Bout's release.
The complicated exchange involved two private planes taking the couple to Abu Dhabi airports from Moscow and Washington, and then flying them home.
Footage in Russian state media - apparently provided by Russian security services - shows them crossing the tarmac with their respective teams.
"Russian citizens have been returned to their homeland," the Russian Foreign Ministry said in a statement.
Speaking in the Oval Office, Brittney Griner's wife Cherelle praised the Biden administration's efforts in securing his release: "I'm just standing here on edge."
According to the joint Saudi-UAE statement, Saudi Crown Prince Mohammed bin Salman played a leading role in the mediation efforts, along with UAE President Mohammed bin Zayed al-Nahyan.
The heir to the Saudi throne has good relations with Russia's Vladimir Putin and in September he helped coordinate the complex exchange of hundreds of prisoners being held by Russia and Ukraine.
The White House, however, denied any mediation was involved. "The only countries negotiating this deal are the United States and Russia," said press secretary Karine Jean-Pierre.
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As negotiations began securing Griner's release over the summer, the US made it clear they wanted ex-marine Paul Whelan to be included in the exchange.
But it became clear that Whelan, who was jailed in 2018 on suspicion of spying, would not be part of the Russian swap, dashing his family's hopes.
Bout's lawyer, Alexei Tarasov, told Russian TV that the US wanted the two citizens back from the start, and the Russian foreign ministry complained that "Washington categorically refuses to engage in dialogue".
Paul Whelan told CNN he was "very disappointed" that nothing had been done to get him released, as he had committed no crime: "I don't understand why I'm still sitting here," he said.
President Biden ended up signing Bout's release order, easing his 25-year prison sentence, in an immediate exchange with Griner.
Bout's wife, Alla, told Russian TV she had only spoken to him two days ago: "He should have called me tonight. Now we will meet and hug. It's better than any phone call."
Viktor Bout sold weapons to rogue warlords and governments, becoming one of the most wanted men in the world.
Nicknamed the "merchant of death" for running guns in the years after the fall of the Soviet Union, Russia's exploits inspired the 2005 Hollywood film Lord of War, which is loosely based on his life.
His secret career was ended by a complicated US raid in 2008, when he was arrested in a hotel in the Thai capital Bangkok, angering the Russian government.
He was extradited two years later and has spent the last 12 years languishing in American prisons for conspiring to support terrorists and kill Americans.
Bout's state was very different from that of his opponent in the prisoner exchange.
Brittney Griner, 32, is one of America's most famous sportswomen. During the US basketball season, the double Olympic champion was center star Phoenix Mercury in the WNBA.
The only reason he flew to Moscow was to play in Russia during the US off season. He told a Russian court that the cannabis oil found in his bag was an "honest mistake".
Secretary of State Antony Blinken singled out the efforts of presidential envoy Roger Carstens, accompanying Griner on the plane from the UAE.
Prominent figures in US basketball welcomed her release, including two-time WNBA champion Breanna Stewart of the Seattle Storm.
Griner was transferred last month to a penal colony in Mordovia, a remote area about 500 km (310m) southeast of Moscow. He is being held not far from where Paul Whelan is serving a 16-year prison sentence on espionage charges.
In his statement, President Biden said Russia had treated Whelan's case differently from Griner's for reasons that were completely illegitimate.
"While we have not succeeded in securing Paul's release, we have not given up; we will not surrender," he vowed.
Whelan's brother, David, praised Griner's release and said US officials had warned the family beforehand that Paul Whelan was not part of the exchange.
"Clearly the US government needs to be more assertive," he said in a statement. "If a bad actor like Russia is going to catch innocent Americans, the US needs a faster and more direct response."
Former White House national security adviser John Bolton condemned the deal as not a swap but a surrender by the Biden administration.
"Terrorists and rogue states around the world will take note of this and that harm other Americans in the future," he said.
The deal was also criticized by Robert Zachariasiewicz, a former US Drug Enforcement Administration agent, who helped lead the team that arrested Viktor Bout.
"Today's actions only target every citizen of the United States traveling around the world and they are just becoming a commodity," he told the BBC's World Tonight.
"I think we just sent the message that it is very good business to illegally detain and if not kidnap Americans, and it is very good to have it in your back pocket if you need it for trafficking at some point."
Vladimir Osechkin - a former Russian lawmaker who led a parliamentary inquiry into Bout, and who is now a dissident in France - told the BBC's Outside Sources program he believes Vladimir Putin wants Bout back because of what he knows.
"Putin and the generals are worried that Viktor Bout may start providing detailed and consistent evidence about what he knows about Russian intelligence aiding terrorist organizations and organizing sabotage abroad," he said.
"It is an honor for them to take back their agent."
Thursday's prisoner exchange was not the first between Russia and the US this year. US Marine Trevor Reed spent three years in prison for assault before being traded last April for Konstantin Yaroshenko, a Russian pilot convicted of cocaine smuggling.
Speaking from a Russian penal colony, Paul Whelan said he had been told the Russians "put me on a higher level than what they did with Trevor and Brittney", because he was accused of being a spy.
President Biden urged Americans to take precautions before traveling abroad, and warned of the risks of being unlawfully detained by a foreign government. This article was written by EDUKASI CAMPUS.