Acting came almost immediately. She made her debut the same year in 9 End 2 Outs, and the 2008 daily drama You Are My Destiny turned her into a leading actress, winning her Best New Actress at the Baeksang Arts Awards along with two prizes at the KBS Drama Awards. Cinderella Man (2009) and Love Rain (2012) opposite Jang Keun Suk followed, then The Prime Minister and I (2013). Her range widened through The K2 (2016), Hush (2020) and Big Mouth (2022), and King the Land (2023) and Bon Appetit, Your Majesty (2025) made her one of the most widely watched actresses of the streaming era.

Her films have been among the biggest in South Korea: Confidential Assignment (2017), Exit (2019) — her first leading film role — and Confidential Assignment 2: International (2022).

She has also released music apart from the group, beginning with the 2016 SM Station single "Deoksugung Stonewall Walkway" with 10cm and the Chinese mini album Blossom, and gathering those songs with "When the Wind Blows", "To You" and "Summer Night" onto her debut EP A Walk to Remember in May 2019, which reached number three on the Gaon album chart. She graduated in theatre studies from Dongguk University in 2015, receiving a lifetime achievement award at the ceremony.