The 41-year-old, whose real name is Nathaniel Hale, had suffered two strokes, one in 2007 and another the following year. Attorney Mark Geragos says the artist died of complications from multiple strokes.
Snoop Dogg, Hale's cousin and a close friend, tweeted, "We lost a true legend n hip hop n rnb. One of my best friends n a brother to me since 1986 when I was a sophomore at poly high where we met."
Several other entertainers also posted tweets to express sadness, including singer Erykah Badu and rappers Ludacris and Xzibit.
Nate Dogg began singing in Long Beach's New Hope Baptist Church choir, but his career, which spanned three decades, started when he joined cousin Snoop Dogg in the trio 213 with Warren G.
Nate Dogg made a name for himself on Dr. Dre's classic album "The Chronic," followed by a breakthrough performance alongside Warren G on the smash record "Regulate," MTV reported on its website. He later released several solo albums, including "G-Funk Classics Vol. 1 & 2."
Funeral plans were not immediately announced.
The Associated Press and City News Service contributed to this report.