The pair were on hand Wednesday at the John Jay College of Criminal Justice in New York to announce the formation of the REFORM Alliance, an organization that aims to reduce the number of people serving unjust parole and probation sentences.
In addition to Jay-Z and Mill, the founding partners include Philadelphia 76ers co-owner and Fanatics executive chairman Michael Rubin, Kraft Group CEO and New England Patriots owner Robert Kraft, Brooklyn Nets co-owner and philanthropic investor Clara Wu Tsai, Third Point LLC CEO and founder Daniel S. Loeb, Galaxy Digital CEO and founder Michael E. Novogratz, and Vista Equity Partners founder, chairman and CEO Robert F. Smith.
Jones said in a statement that the job "is the opportunity of a lifetime."
"I have spent my entire adult life preparing myself to help lead an initiative of this magnitude," he said. "I'm looking forward to working with this powerful group of founders to disrupt the status quo and shift the criminal justice system landscape for generations to come."
Both Jay-Z and Mill have been outspoken in their advocacy for criminal justice reform.
In 2017 Mill received a 2- to 4-year prison sentence for violating probation on a 2008 gun and drug case.
He was arrested in 2017 after being involved in a fight and then again in another incident that involved him popping wheelies on a dirt bike.
Since then, Mill has taken up the fight to make sure others don't receive a similarly harsh sentence.
"I got caught up in the system and every time I started to further my life with the music industry ... every year or two it was something that brought me back to ground zero, and it was probation," Mill said during Wednesday's press conference to announce the alliance.
Jay-Z was one of several celebs who rallied around Mill while he was jailed.
On Wednesday he said the pair had grown up in an environment where they witnessed the unevenness of such a system when it comes to people of color.
"We want to be very clear, if someone commits a crime they should go to jail," Jay-Z said. "But these things are just disproportionate and the whole world knows it."