The author and activist is said to have been in poor health, and was found dead by her caretaker on Wednesday morning.
News of her death comes days after she canceled a May 30 appearance to accept an award. She was to be honored with the "Beacon of Life Award" at the 2014 MLB Beacon Award Luncheon in Houston.
Angelou was born in St. Louis, Mo., in 1926, and published her first book in 1969. The book was her famed autobiography, I Know Why the Caged Bird Sings, and she would go on to write six more autobiographies during her lifetime. Her most recent, Mom & Me & Mom, was published in 2013.
In addition to being an author, Angelou was a celebrated poet, educator and civil rights activist. She received more than 20 honorary degrees from institutions such as Boston College and Tufts University, and was granted the first lifetime Reynolds Professorship of American Studies at Wake Forest University in 1982.