The reality TV star posted a message on her social media accounts following her birthday celebrations on Monday.
"I got amazing gifts from my whole family and Kanye [got] me the most amazing bags," she said. "But he also donated $1 million to my favorite charities that work so hard on prison reform on my behalf from him and the kids. This makes my heart so happy!"
A photo of the donation certificate showed the money has gone to Cut 50, the Buried Alive Project, Equal Justice Initiative and the Anti-Recidivism Coalition, as a gift from West and the couple's four children, North, Saint, Chi and Psalm.
Kardashian said she had had the "best most relaxing birthday ever" following a weekend in Palm Springs with her friends and a family dinner thrown by West and her mother, Kris Jenner.
The Keeping Up With The Kardashians star started studying law last year after lobbying the White House for clemency for Alice Marie Johnson, who served more than two decades of a life sentence without parole for non-violent offences.
President Donald Trump commuted her sentence and signed bipartisan legislation that gives judges more discretion when sentencing some drug offenders and boosts prisoner rehabilitation efforts.