"Thank you to all the artists, friends and partners for helping to bring this all to fruition.. in honor of wonderful Malcom.. who is in all of our hearts," she wrote.
In a statement, Karen said: "The support we've experienced is evident in this amazing lineup and is a testament to Malcolm's incredible life.
"His Father, brother and I are beyond thankful to everyone who is working to make this concert happen along with every fan and every friend for continuing to support Malcolm and his vision.
"He was a caring, loving human with a smile that could light up the sky and a soul that was out to make the world a kinder place and the MMCF will continue to do just that."
Watch the concert here
And below, read everything you need to know about Mac Miller: A Celebration of Life including who's performing and what it's all about.
Where is the concert?
The concert is taking place at The Greek Theater in Los Angeles.
Who is performing?
Mac Miller's close friends and collaborators will perform at the concert on October 31.
These include Action Bronson, Anderson.Paak, Chance the Rapper, John Mayer, J.I.D., Miguel, Njomza, Schoolboy Q, SZA, Thundercat, Travis Scott, Ty Dolla $ign, Domo Genesis, Dylan Reynolds, Earl Sweatshirt, Thundercat and Vince Staples.
What is the Mac Miller Circles Fund?
The Mac Miller: A Celebration of Life concert has been organised to benefit the Mac Miller Circles Fund, with the money going to "provide programming, resources and opportunities to youth from underserved communities, helping them recognize their full potential through exploration in the arts and community building".
Mac Miller's death
Mac Miller died in his home in Los Angeles on September 7, 2018 at the age of 26 from a suspected drug overdose.
A statement from the family at the time read: "Malcolm McCormick, known and adored by fans as Mac Miller, has tragically passed away at the age of 26. He was a bright light in this world for his family, friends and fans. Thank you for your prayers. Please respect our privacy. There are no further details as to the cause of his death at this time."
Following his death many celebrities paid tribute to the rapper. Donald Glover, aka Childish Gambino, dedicated a performance of Riot to the musician, saying: "He was so nice. He was the sweetest guy; he was so nice," before adding: "I just wanna say, I love you, Mac, and I just want to tell you that I love you and this song is for him because I feel like sometimes he wanted to let go."
Other tributes came from everyone including Elton John, Drake, J. Cole, One Direction's Niall Horan, Maroon 5 and Liam Gallagher.
Mac Miller's ex-girlfriend Ariana Grande broke her silence several days after Miller's death, posting on Instagram: "i adored you from the day i met you when i was nineteen and i always will. i can't believe you aren't here anymore. i really can't wrap my head around it.
"We talked about this. so many times. i'm so mad, i'm so sad i don't know what to do. you were my dearest friend. for so long. above anything else. i'm so sorry i couldn't fix or take your pain away. i really wanted to. the kindest, sweetest soul with demons he never deserved. i hope you're okay now. rest."
