The 41-year-old passed away in Long Beach, Calif., in the early hours of Tuesday morning, according to his family.
The cause of his death is not yet known, but the hip-hop star spent the last few years struggling to recover from a series of strokes, which paralyzed him down the left side of his body.
Snoop Dogg says his longtime friend and former 213 bandmate will be sadly missed.
In a series of posts on his Twitter page, he writes, "We lost a true legend n hip hop n rnb. One of my best friends n a brother to me … I love u buddy luv. U will always b wit me 4ever n a day u put the g n g funk u put the 1 n 213 … I miss u ... I am so sad but so happy I got to grow up wit u and I will c u again n heaven cuz u know d slogan … all doggs go to heaven... RIP Nate Dogg."
50 Cent, who collaborated with the star on "21 Questions" and other hits heard the news as he stepped off a flight from Los Angeles to New York and wrote, "I just landed, Nate Dog is dead damn. God bless him R.I.P. He meant a lot to West Coast hip-hop ... RIP Nate Dogg, the rap world just lost a great legend ... I wrote the chorus to '21 Questions' I needed Nate to sing it for me. He had a way of making everything feel hard."
Ludacris, who worked with Nate Dogg on 2001 single "Area Codes," adds, "There is a certain void in hip-hop's heart that can never be filled. Glad we got to make history together."
While The Game writes, "R.I.P. Nate Dogg. Why does it take Death to remind us about the importance of life ??? Cherish every moment cuz tomorrow he mite call your # ... I lost a friend. Been here before. Tears. Memories. One day someone will lose 'US' as well. Living until that day comes is our only option."
Rapper Xzibit writes, "We love you Nate Dogg, it's never going to be the same," and singer Erykah Badu adds, "Nate Dogg ... Rest in beats."