Meek Mill isn't gonna let being behind bars stop him from joining Colin Kaepernick's cause ... becoming the latest celeb to team with Kaepernick on his $10k for 10 days initiative.
You might've heard -- for the final $100k of Colin's $1 million pledge for social justice, Kaep's been partnering with huge names in sports and entertainment to match his individual $10k donations.
So far, Serena Williams, Snoop Dogg, Steph Curry and Kevin Durant have all stepped up.
And now, Colin's second-to-last donation has come from the imprisoned rapper -- who's serving 2 to 4 years for a probation violation Kaep's spoken out against in the past.
"Despite my brother’s current circumstances, he continues to stay involved and connected in the community of his hometown of Philly," Colin said.
"I’ve spoken to Meek several times since his incarceration and during one of these calls, is when he pledged ... we’re both donating $10,000 each for a combined $20,000 to Philadelphia’s Youth Service Inc."
Respect.