Lee Chung-ah debuted as an actress with a minor role in the 2002 action film Resurrection of the Little Match Girl. In 2004, she acted alongside Jo Han-seon and Kang Dong-won in the movie Temptation of Wolves, which won her Best New Actress at the Golden Cinematography Awards and the Grand Bell Awards in 2005. In 2007, she starred in the romantic comedy film My Tutor Friend 2, opposite Park Ki-woong. In 2009, she appeared in the KBS dramas Accidental Couple and Everybody Cha Cha Cha, which both gave her a Best New Actress nomination at the KBS Drama Awards. In 2011, she took on the female leading role in tvN’s Flower Boy Ramyun Shop. In 2016, she joined the main cast of the MBC series Lucky Romance, which earned her an Excellence Award nomination at the MBC Drama Awards. In 2019, she was named Best Supporting Actress at the SBS Drama Awards for the mystery melo series VIP.

Lee Chung-ah attended Hanyang University. Her father Lee Seung-chul is also an actor. She previously dated Lee Ki-woo, who she co-starred with in Flower Boy Ramyun Shop.