Over the past few months, Kardashian has been in talks with Kushner - whose job description has included fixing the criminal-justice system, as well as the Middle East, veterans affairs, Chinese diplomacy and the opioid crisis - about Johnson's case.
According to Vanity Fair, Kardashian first contacted Ivanka Trump, also a White House adviser, about the issue, and Trump connected the Keeping Up With the Kardashians star to her husband, Kushner.
At a White House event on prison reform earlier this month, Kushner said that "the single biggest thing that we want to do is really define what the purpose of a prison is. Is the purpose to punish, is the purpose to warehouse or is the purpose to rehabilitate?"
Kushner has a personal connection to the issue. His father, real estate developer Charles Kushner, served a year in a federal prison for tax evasion and illegal campaign contributions.
Congress, with Jared Kushner's urging, passed the First Step Act last week, a bill aimed at lowering the recidivism rate by earmarking US$50 million annually for educational and vocational training and mental-health treatment in federal prisons.
"Where I'm at in my life right now, just like, to go and spend my money buying material things just doesn't satisfy me the way that it used to," Kardashian said in an interview with Mic, which reported on Johnson's case in 2017. "To save someone's life and do that once a year, then that would make (my) heart fuller."
In a letter written to Kardashian and obtained by TMZ, Johnson thanked the reality star for her efforts, including the help of Holley, who was once a member of OJ Simpson's "dream team" alongside Kardashian's late father, Robert Kardashian.
"Ms Kardashian you are literally helping to save my life and restore me to my family," she wrote. "I was drowning and you have thrown me a life jacket and given me hope."
"This is so much bigger than either of us," Johnson wrote in the letter, which also referenced civil rights icon Rosa Parks. "I believe that history will record that Kim Kardashian had the courage to take a stand against human warehousing and was a key figure in meaningful criminal justice reform becoming a reality."