XXXTentacion, whose real name was Jahseh Onfroy, was gunned down in Florida last week at the age of 20.
Mill, who was released from prison earlier this year, wore a hoodie bearing the rapper’s image while he performed Stay Woke.
The performance referenced police violence against African American youths as well as prison reform.
Revered R&B artist Anita Baker was honoured with the Lifetime Achievement Award and used her acceptance speech to urged musicians to support each other.
The 60-year-old appeared emotional as she watched Foxx, Yolanda Adams, Ledisi and Marsha Ambrosius perform her hits including Caught Up In The Rapture, Angel and Sweet Love.
After being called to the stage to accept the award, the seven-time Grammy winner, who dominated the R&B charts from the early 1980s through to the mid-90s, told young stars to tap veterans on the shoulder and ask for their advice.
She added: “I would ask that the music be allowed to play, that singers are allowed to sing, and rappers are allowed to rap, and poets are allowed to rhyme.”
Jamie Fox hosted the annual awards ceremony, which celebrate African Americans and other American minorities in music, film and sports, for the second time. Elsewhere, Kendrick Lamar won the Best Male Hip Hop Artist Award while Cardi B won the female equivalent.
Video Of The Year went to Drake for God’s Plan.
Among the winners on the night were DJ Khaled, Bruno Mars and Migos while Nicki Minaj performed.
Black Panther was honoured at the BET Awards as Meek Mill debuted a new song and paid tribute to XXXTentacion.
Superhero blockbuster Black Panther scooped the Best Movie Award and during his acceptance speech at the Microsoft Theatre in Los Angeles, director Ryan Coogler urged audiences to visit Africa, saying his journey there “changed my life”.
He said: “The film is about our experience of being African Americans and trying to capture the experience of being African on this planet… with so many factors telling you it’s something you should be ashamed of.
“It was about tapping into that voice that tells us to be proud of who we are and proud of where we came from.”