The iconic musician has been "fighting Merkel Cell Skin Cancer for four years," according to an official obituary on his website.
According to the National Cancer Institute, Merkel cell carcinoma is a highly rare condition in which malignant (cancer) cells grow in the skin.
According to the website, "sun exposure and having a weak immune system can affect the risk of Merkel cell carcinoma."
Buffett "continued to perform during treatment," according to the obituary, "playing his last show, a surprise appearance in Rhode Island, in early July.
On September 1, the "Margaritaville" celebrity died at his home in Sag Harbor, Long Island. He was 76 years old at the time.
According to a statement put on his website and social media pages, he died peacefully surrounded by his family, friends, music, and pets.
"He lived his life like a song till the very last breath and will be missed beyond measure by so many," the statement says.
Buffett is survived by Jane Slagsvol, his wife of 46 years, and their three daughters, Savannah, Sarah, and Cameron.