"BEST NEWS EVER!!!!" was the Twitter response from Kardashian West.
She became an ordained minister while behind bars and mentored women in prison. She was released hours later and ran into her family members' arms.
Michael Scholl, a member of Johnson's legal team, said she was released just before 6pm from federal prison in Aliceville, Alabama. Relatives were there to greet her as she experienced freedom for the first time since the 1990s.
Footage from local news station WVTM-13 showed Johnson running towards her family, throwing her arms wide open and embracing them in front of a crowd of onlookers.
"Everybody was crying and hugging," Mr Scholl said.
Unlike a pardon, the commutation will not erase Johnson's conviction, only end her sentence.
Mr Scholl said Johnson would be returning to Memphis and was planning to spend time with her family. He earlier praised Mr Trump for "a courageous move" and described Johnson as overwhelmed by the news.
Mr Trump's decision comes amid a recent flurry of pardons issued by the president, who has seemed drawn to causes advocated by conservatives, celebrities or those who once appeared on his former reality show The Apprentice.
This use of executive power is taking place against the backdrop of the Russia investigation that hangs over his presidency.
The White House said Johnson had "accepted responsibility for her past behaviour" and had been a model prisoner, working hard to rehabilitate herself and serve as a mentor to fellow inmates.
It said that Johnson's warden, case manager, and vocational training instructor had written letters in support of her clemency.
"While this Administration will always be very tough on crime, it believes that those who have paid their debt to society and worked hard to better themselves while in prison deserve a second chance," according to a statement from the office of White House spokeswoman Sarah Huckabee Sanders.
Kardashian West has expressed gratitude.
So grateful to @realDonaldTrump, Jared Kushner & to everyone who has showed compassion & contributed countless hours to this important moment for Ms. Alice Marie Johnson. Her commutation is inspirational & gives hope to so many others who are also deserving of a second chance.— Kim Kardashian West (@KimKardashian) June 6, 2018
The commutation puts a renewed focus on the Trump administration's push for prison and sentencing changes, an effort that sometimes has clashed with the president's law-and-order approach, especially at the Justice Department.
Mr Trump has called for getting tougher on drug dealers, including suggesting some should receive the death penalty.
The phone call I just had with Alice will forever be one of my best memories. Telling her for the first time and hearing her screams while crying together is a moment I will never forget.— Kim Kardashian West (@KimKardashian) June 6, 2018
Johnson was convicted in 1996 on eight criminal counts related to a Memphis-based cocaine trafficking operation involving more than a dozen people.
The 1994 indictment describes dozens of deliveries and drug transactions, many involving Johnson.
She was sentenced to life in prison in 1997.
Appeals court judges and the Supreme Court rejected her appeals.
Court records show she has a motion pending for a reduction in her sentence, but federal prosecutors are opposed, saying in a court filing that the sentence is in accord with federal guidelines, based on the large quantity of drugs involved.
A criminal justice advocacy site, CAN-DO, and one of Johnson's lawyers said a request for clemency was rejected when Barack Obama was president. The reasons are unclear.
A 1997 Associated Press story on Johnson's sentencing said she headed up a multimillion-dollar drug ring.
However, Memphis lawyer Mr Scholl, who filed the latest court documents in her request for a sentence reduction, said she was not a leader in the cocaine operation.
"What is the purpose of putting a lady with no prior criminal record, on a non-violent drug offence, in jail for her entire life?" he said in a telephone interview. "She's a model inmate."
Mr Scholl said Johnson had admitted her wrongdoing, which is borne out in letters she had written to US District Judge Samuel H Mays, who now oversees her case.
"Judge Mays, I'm writing to you to express my deep remorse for the crime that I committed over 20 years ago.
"I made some bad choices which have not only affected my life, but have impacted my entire family," she said in a February 2017 letter in the court record.
In a hand-scrawled letter last June she wrote: "I'm a broken woman. More time in prison cannot accomplish more justice."
Kardashian West visited the White House in May to meet with Jared Kushner, Mr Trump's son-in-law and senior adviser, who is overseeing the administration's push to overhaul the nation's prison system.
She also met with Mr Trump in the Oval Office, a photograph of which the president released on Twitter.
In an interview with Mic, a digital news company, released this year, Kardashian West said she was moved by Johnson's story after seeing a video by that outlet on Twitter.
"I think that she really deserves a second chance at life," she told Mic. "I'll do whatever it takes to get her out."
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