Hyeri, along with Yura, joined the South Korean girl group Girl’s Day as replacements to original members Jisun and Jiin, who left the band just two months after their debut in 2010. In March 2013, the group released their first studio album called Expectation, which was later re-released under the title Female President. In 2014, the song Something from their fourth extended play Everyday 3 became their highest-charting single, peaking at No. 2 on both the Billboard’s K-Pop Hot 100 and the Gaon Digital Chart. The single’s music video also reached over a million views in just one day. In 2015, Girl’s Day ranked 13th in Forbes Korea’s Power Celebrity List.

Hyeri made her acting debut in the 2012 SBS weekend drama Tasty Life. In 2014, she won Best Female Newcomer at the MBC Entertainment Awards for her appearance on the variety show Real Men. She also earned the nickname “Nation’s Little Sister” for the viral aegyo that she displayed on the program. In 2015, she was cast as lead in the tvN series Answer Me 1988. It recorded a peak viewership rating of 18.8 percent, making it one of the highest-rated Korean cable television dramas of all time. She won Best New Actress at the 5th APAN Star Awards and also scored a Best New Actress nomination at the 52nd Baeksang Arts Awards for her work in the series. In 2016, she placed 3rd in Forbes Korea’s Power Celebrity List. In 2017, she was cast as the female lead in the movie Monstrum, which also served as her big screen debut. In 2021, she starred in the tvN fantasy romantic comedy My Roommate Is a Gumiho, opposite Jang Ki-yong.

Hyeri dated her Answer Me 1988 co-star Ryu Joon-yeol for six years.