Elizabeth Mitchell was born Elizabeth J. Robertson in Los Angeles, California; Elizabeth Mitchell stepfather Joseph Day Mitchell's and mother Josephine Marian Mitchell are lawyers based in Dallas.
Elizabeth Mitchell moved with her mother to Dallas, Texas in 1970, where in 1975 her mother married Joseph Mitchell. Elizabeth Mitchell graduated from Booker T. Washington High School for the Performing and Visual Arts, a public magnet school.
Elizabeth Mitchell is the oldest of three sisters, the others being Kristina Helen "Kristie" Mitchell and Katherine Day "Kate" Mitchell. In 1991, Elizabeth Mitchell graduated from Stephens College with a Bachelor of Fine Arts. Elizabeth Mitchell worked for six years in Dallas Theater Center and a year at Encore Theater.
Elizabeth Mitchell had a recurring role as Dr. Kim Legaspi, the first lesbian lover of Dr. Kerry Weaver, during the 2000-2001 season of the TV series ER.
Elizabeth Mitchell married actor Chris Soldevilla on 13 June 2004. They have a son, Christopher Joseph (C.J), who was born on September 4, 2005. They live on Bainbridge Island, Washington.