On his "first day out" of prison, Meek Mill pledged to fight for others. Months after the Philadelphia Supreme Court ordered his release in April, the rapper continues to make good on his promise.

Joining forces with leaders in the music, sports and business world, including hip-hop mogul Shawn “Jay-Z” Carter, Meek announced on Wednesday the launch of REFORM Alliance, a new criminal justice reform organization chaired by himself and his friend, Philadelphia 76ers owner Michael Rubin.

"I'm here to speak for all the people who don't have a voice," Meek Mill, whose full name is Robert Rihmeek Williams, said at the event.

"I got caught up in the system and every time I started to further my life with the music industry — from traveling the world, performing worldwide and actually making money to be able to provide for my family and take them out of their ruthless environment, every year or two was something that always brought me back to ground zero and it was probation and I always wondered what happened to people in situations worse than mine," he said.

The organization, which will be led by longtime criminal justice reform advocate and CNN commentator Van Jones, aims to "drastically reduce the number of people who are under control of the criminal justice system by changing laws and public opinion," according to a press release shared with ABC News.

Jay-Z applauded Meek's activism and said the rapper's story "sparked the match for the nation."

"We're all prisoners to this because until everyone's free, no one's free," Jay-Z says at the launch of @REFORM pic.twitter.com/diEX6I7ppo

— Deena Zeina Zaru ??????? (@Deena_Zaru) January 23, 2019

Meek, who is signed to Jay-Z's label, Roc Nation, was sentenced to two to four years in prison last November after a pair of arrests that violated his probation from a 2008 gun and drug case. This sentence for technical violations sparked outrage among criminal justice reform advocates and invigorated a national debate on probation laws and mass incarceration.

In a passionate speech on Wednesday, Rubin said that he argued with Meek for years about the criminal justice reform system because Rubin thought it "worked great," but Meek's experience taught him that he "could not have been more wrong."

"It was honestly the most surreal moment of my life. I didn't think this could happen to anybody," Rubin said. "I looked at Meek and I looked at his mom and I said I will not stop; Jay-Z said he would not stop until Meek was out of prison," he added.

For activists, the issue was not whether Meek violated his probation but whether the now 31-year-old rapper, who had already served an eight month sentence when he was convicted for drug and gun possession at 19, should still be on probation.

Amid the outrage, Jay Z wrote an op-ed for The New York Times criticizing probation laws and wrote, "What’s happening to Meek Mill is just one example of how our criminal justice system entraps and harasses hundreds of thousands of black people every day."

The Pennsylvania Supreme Court ordered Mill's immediate release on "unsecured bail" in April, citing "credibility issues with a police officer who was a 'critical witness'" in Mill's case. But his request for a new trial was denied in June and he is still on probation.

“I just wanna get off probation I been on this s--- my whole adult life ... 11 years of asking for permission,” he tweeted on Tuesday.

And this is one of the issues that REFORM Alliance hopes to tackle.

The organization's high-powered executive board is made up of co-founders Shawn “JAY-Z” Carter, 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 chairman and CEO Robert F. Smith.

Both Rubin and Kraft visited Meek while he was in prison and were strong advocates for his release.

"What started as a sole focus to save my friend from prison has now evolved into a much bigger mission to fix a fundamentally broken system while keeping communities safer," Rubin said in a statement provided to ABC News. "We’re committed to making a monumental difference with this alliance and create the necessary reform that our country deserves.”

"I had never been to jail before and going there and seeing him, I didn't sleep the rest of the night when I went home because here I thought how out of touch someone like myself is with what's really going on"," Kraft said while speaking at the event.

In the months leading up to the launch, Meek has quickly become one of the most visible advocates for criminal justice reform on the national stage and has joined PUMA’s #REFORM campaign as an ambassador for criminal justice reform.

The rapper told ABC News in August that he was energized by the support of his fans and grateful for activists who supported the #FreeMeekMill campaign and is now hoping to lend his platform to those who don’t have a voice.

“Creating the REFORM Alliance is one of the most important things I’ve ever done in my life. If you thought my case was unfair, there are millions of others dealing with worse situations and caught up in the system without committing crimes. With this alliance, we want to change outdated laws, give people hope and reform a system that’s stacked against us,” he said in a statement provided to ABC News.

The founding partners of "Reform Alliance", a newly formed organization to reform the U.S. criminal justice system, (L-R) Shawn "Jay-Z" Carter, Robert Kraft, Michael Rubin, Meek Mill, Michael E. Novogratz, Clara Wu Tsai, Daniel S. Loeb and Reform Alliance CEO Van Jones pose together at the Reform Alliance launch event in New York, Jan. 23, 2019.(Mike Segar/Reuters) The founding partners of "Reform Alliance", a newly formed organization to reform the U.S. criminal justice system, (L-R) Shawn "Jay-Z" Carter, Robert Kraft, Michael Rubin, Meek Mill, Michael E. Novogratz, Clara Wu Tsai, Daniel S. Loeb and Reform Alliance CEO Van Jones pose together at the Reform Alliance launch event in New York, Jan. 23, 2019.

Criminal justice reform is one of the rare issues these days that has some bipartisan support in Congress and even has advocates in the White House, including President Donald Trump and his son-in-law, Jared Kushner.

Trump urged Senate Majority Leader Mitch McConnell to bring a landmark criminal justice reform legislation to the Senate floor for a vote in December and after it cleared the Senate, it easily passed in the House of Representatives.

The First Step Act expands job training and programs to help reduce recidivism rates among federal prisoners and allows judges to sentence below the mandatory minimum for qualified low-level nonviolent drug offenders who cooperate with the government. It also reduces the second strike mandatory minimum of 20 years to 15 years, and reduces the 3rd strike mandatory minimum of life in prison to 25 years.Landmark criminal justice reform bill clears Senate

When asked by ABC News in September if he would be willing to speak with Trump to advocate for criminal justice reform, Meek said, “I’m always open to talking to the president to make change. Everybody I was in prison with always encouraged me to go, take the sacrifice, even if you get crucified in the media — go, try to make change."