Huffman was born in Bedford, New York, the daughter of Grace Valle (née Ewing), an actress, and Moore Peters Huffman, a banker and partner at Morgan Stanley. Her parents divorced a year after her birth, and she was raised mostly by her mother. She has six sisters (Mariah, Betsy, Jane, Grace, Isabel, Jessie) and a brother (Moore Jr.). She attended The Putney School, a private boarding high school in Putney, Vermont and graduated from Interlochen Arts Academy in Michigan in 1980. After high school she went on to New York University where she graduated in 1984 from Circle In The Square, with a Bachelor of Fine Arts in Drama.