She was born in Chicago, Illinois, to John Young Shipka, a real estate developer, and his wife, Erin Ann , a one-time queen of Chicago's St. Patrick's Day parade. The family relocated to Los Angeles when she was six to support her acting career.Kiernan got her black belt in taekwondo in June, 2012.
Shipka's hobbies include golf and cooking. She enjoys watching Barefoot Contessa and Good Eats on the Food Network and she has been taking ballroom dancing classes since age 5. She claims Grace Kelly as an inspiration.
Shipka began doing commercial print modeling when she was a baby.
As part of Mad Men's ensemble cast, she won the Screen Actors Guild Award for Outstanding Performance by an Ensemble in a Drama Series in 2008 and 2009.
Shipka's individual performance on Mad Men has been well received. In naming her as his dream nominee for the "Outstanding Guest Actress in a Drama Series" Emmy Award, Austin American-Statesman critic Dale Roe remarked, "This 10-year-old actress was so affecting as troubled Sally Draper last season that it seems odd that she's only just been upgraded to series regular. If Shipka's upcoming Mad Men work—struggling with the broken marriage of her parents and entering preteendom in the tumultuous 1960s—remains as amazing as it was in season three, this is a ballot wish that could come true next year. Initially a recurring guest star, Shipka was upgraded to a series regular with the start of season four.
Shipka played Cathy in Flowers in the Attic, which premiered on January 18, 2014.