The WNBA star has spent the last 10 months in prison in Russia after she was detained at an airport back in February for allegedly carrying illegal cannibas oil in her luggage.
US officials revealed on Thursday that, following weeks of negotiations, a one-for-one swap had been carried out, exchanging the 32-year-old American basketball star for Bout.
Ms Griner’s family, friends and fans – alongside many public figures – have been calling on Russia to free her for months and for the US State Department to intervene.
Here's everything we know about the ordeal:
Who is Brittney Griner?
Ms Griner plays for the Phoenix Mercury WNBA team as a centre.
She also formerly competed with the US Olympic basketball team in 2016 winning gold at the Rio Games and picking up her second winner’s medal in Tokyo last summer.
She is an accomplished basketball player, earning a Best Female Athlete award at the ESPYs and an endorsement deal with Nike in 2013.
On 17 February, Ms Griner was traveling through the Sheremetyevo International Airport in Moscow when Russian customs officials allegedly found cartridges containing the offending hashish oil in her luggage.
Ms Griner was taken into custody at the airport on charges of large-scale transportation of illegal narcotics, which carried a sentence of up to 10 years in prison.
Her detainment occurred shortly before Russia launched its war in Ukraine, with geopolitical tensions making it undoubtedly more difficult to secure her release.
Her trial began on 1 July with the Russian government presenting evidence that the WNBA star “bought two cartridges for personal use, which contained 0.252 grams and 0.45 grams of hash oil,” according to a courtroom report from state news agency Tass.
The trial resumed on 7 July, with Ms Griner clutching a photo of her wife Cherelle.
Ms Griner pleaded guilty to the charges.
“I’d like to plead guilty, your honour. But there was no intent. I didn’t want to break the law,” Ms Griner said, speaking English which was then translated into Russian for the court.
“I’d like to give my testimony later. I need time to prepare.”
In early August, Ms Griner was sentenced to nine years behind bars. She filed an appeal of her conviction, which was taken up at a hearing on 25 October. At that appeal, a Russian court upheld their sentence with a prosecutor calling it “fair.”
On 17 November, Griner was relocated to a penal colony in Mordovia, about 350 kilometers (210 miles) east of Moscow.
“Brittney is doing as well as could be expected and trying to stay strong as she adapts to a new environment,” her lawyers said in a statement.
Ms Griner’s lawyer, Alexandr Boykov, toldThe New York Times that his client “has not been in as good condition as I could sometimes find her in” in recent weeks.
Why was she in Russia?
Ms Griner had been in Russia to play basketball in the Russian Premier League.
Many American athletes travel overseas during the US off-season to continue competing in their chosen sport.
The off-season foreign leagues provide American athletes with additional money-making opportunities and a chance to keep their skills sharp through continuous competition.
WNBA stars like Ms Griner typically make, on average, a mere 1.5 per cent of the salary that their male counterparts in the NBA make in a year, so playing outside of the US often helps make up for that pay disparity.
Ms Griner reportedly earns $1m per season she plays in Russia while her base salary at the Phoenix Mercury is said to be $221,450.
The fight for her freedom
Supporters of Ms Griner, alongside her family and friends, called for her release for months.
In June, the White House offered to exchange Ms Griner and another detained American, Paul Whelan, for Viktor Bout, an infamous Russian arms dealer serving a federal prison sentence in the US for conspiring to sell arms to a Colombian rebel group deemed a terrorist organisation.
In mid-September, US officials said Russia hasn’t responded to the offer.
“We have made a serious offer to get Brittney Griner and Paul Whelan back home,” National Security Council spokesperson John Kirby said on 16 September. “The Russians have not responded to that offer. But that doesn’t mean that we’re not still in negotiations and we’re not still trying.”
Mr Kirby made the comments just before President Joe Biden met with Ms Griner’s family, including her wife Cherelle.
“I want to thank President Biden for yesterday’s meeting as well as the Administration for its efforts to secure my wife’s release,” Cherelle Griner wrote in the caption of an Instagram post with a photo of herself and the president. “It was an honor to speak with him directly about the Brittney we know and love. I’ve felt every minute of the grueling seven months without her. I look forward to the day my wife is back home.”
“As my family and I continue on this journey, I’d like to thank the broad coalition of friends, leaders and supporters who continue to stand with us and advocate for Brittney’s swift and safe return,” she added. “Let’s share a unified commitment to bringing all Americans home to their families and loved ones.”
Ms Griner addressed Mr Biden directly in a letter prior to her July trial, writing: “As I sit here in a Russian prison, alone with my thoughts and without the protection of my wife, family, friends, Olympic jersey, or any accomplishments, I’m terrified I might be here forever.”
On Thursday (8 December), US officials confirmed that Ms Griner had finally been released in a prisoner exchange for Russian arms dealer Viktor Bout.
Washington and Moscow had been negotiating the one-for-one swap for several weeks, before Mr Biden gave the final sign-off over the last week.
Mr Whelan, who was expected to be part of a prisoner exchange with Russia, remains behind bars.
The exchange took place in the United Arab Emirates on Thursday.
Mr Biden celebrated the news on Twitter, along with photos of himself, with Ms Griner’s wife Cerelle Griner, and Vice President Kamala Harris at the Oval Office.
“Moments ago I spoke to Brittney Griner. She is safe. She is on a plane. She is on her way home.”
In a press briefing minutes later, Ms Griner’s wife celebrated the news while Mr Biden vowed that the US has “not forgotten” about Mr Whelan.
“We have not forgotten about Paul Whelan. This was not a choice about which American to release. Russia is treating Paul’s case differently … we are not giving up,” he said.