She was born in St. George, Utah and raised in Las Vegas, Nevada, subsequently moving to Los Angeles to seek further acting opportunities. She married actor Jordan Alan on April 29 2006. Amanda is the youngest of eight children, having six sisters and one brother.
After securing a role in the pilot No Place Like Home, Righetti caught the eye of Fox executives. She played a regular guest character Hailey Nichol in the American teen drama The O.C. In the season finale of Season 2 of The O.C., her ex-boyfriend Jimmy Cooper jokes about life on the North Shore, the show she formerly starred in after the series was canceled after one season, playing the role of Tessa Lewis.
In late 2005, Righetti starred in FOX's Reunion as Jenna Moretti.