Im Se-mi debuted as an actress in the 2005 KBS2 series Sharp 2. In 2007, she landed her first big screen appearance in the musical comedy film Highway Star. In 2011, she played supporting roles in You’ve Fallen for Me and Hooray for Love, which both aired on MBC. In 2014, she joined the main cast of the SBS daily drama I Only Want to Love. In 2015, she starred alongside Park Jin-woo in KBS2’s Love on a Rooftop, which earned her an Excellence Award nomination at the KBS Drama Awards. In 2016, she became part of the romantic comedy series Shopping King Louis, which won her a Golden Acting Award at the MBC Drama Awards. In 2017, she was nominated for an Excellence Award at the MBC Drama Awards for Two Cops. In 2018, she received another Excellence Award nomination at the MBC Drama Awards for My Secret Terrius. In 2020, she portrayed Moon Ga-young’s sister in the hit tvN series True Beauty.

Im Se-mi graduated from Jinseon Girls’ High School and continued her education at Dongduk Women’s University.