Miller, 26, was found at his San Fernando Valley home and was pronounced dead at the scene, TMZ reports.
"He was a bright light in this world for his family, friends, and fans", his family said in a statement. Further details are now unclear.
Miller was born Malcolm James McCormick in Pittsburgh, Pennsylvania.
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Pittsburgh native Wiz Khalifa tweeted, "Praying for Mac's family and that he rest easy". Having already gained a following via mixtapes, touring and singles like "Donald Trump", his debut, "Blue Slide Park", released in 2011, entered the Billboard album chart at #1. Two years later he started the label REMember Music and released his sophomore album "Watching TV with the Sound Off". Records, his first major labor.
He was scheduled to start his US tour in San Francisco on October 27th. The album debuted in the third spot on the Billboard 200 chart.
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Miller had been in a long-term relationship with Ariana Grande, which ended this past May. After their breakup, she voiced her concern about his health.
In May, Miller was arrested for a misdemeanor DUI. Just last month, the Los Angeles Attorney's Office officially charged the rapper with a DUI stemming from a vehicle accident in May in the San Fernando Valley. Starting in 2013, he starred in his own MTV2 reality series, "Mac Miller and the Most Dope Family", which ran for two seasons.
Chance the Rapper, Khalid and Shawn Mendes swiftly paid tribute on Twitter.
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