Lee Seung-gi debuted as a singer in 2004 with the studio album The Dream of a Moth, which spawned the hit single Because You’re My Woman. The song won him numerous awards, including Best New Male Artist at the 2004 Mnet Km Music Video Festival. His music career soared higher with a string of successful albums such as 2004’s Story of Separation, 2009’s Shadow, and 2011’s Tonight. In 2012, he made his Japanese debut with the album Alone in Love. That same year, he released his first extended play titled Forest, which produced the top-charting single Return. The song earned him the Best Male Vocal Performance citation at the 2013 Mnet Asian Music Awards. In 2020, he made his comeback to the music scene with the release of his seventh studio album The Project.

Lee Seung-gi made his official acting debut in the 2006 KBS2 weekend series Famous Princesses. In 2009, he starred opposite Han Hyo-joo in the hit SBS drama Brilliant Legacy, which won him numerous awards, including the Baeksang Most Popular Actor for TV. In 2010, he was paired with Shin Mina in SBS’s My Girlfriend Is a Gumiho, which gave him an Excellence Award at the SBS Drama Awards. In 2012, he acted alongside Ha Ji-won in MBC’s The King 2 Hearts. In 2013, he received a Top Excellence Award at the MBC Drama Awards for the fantasy fusion sageuk Gu Family Book. In 2014, he joined Cha Seung-won and Go Ara in the SBS drama You’re All Surrounded. In 2017, he led the cast of the tvN fantasy series Hwayugi. In 2019, he reunited with his Gu Family Book co-star Suzy in the SBS series Vagabond, which scored him a Top Excellence Award at the SBS Drama Awards. In 2021, he took home the Daesang at the Asia Artist Awards for tvN’s Mouse.

Aside from singing and acting, Lee Seung-gi is also active in entertainment programs. He was a fixed cast member of KBS2’s 1 Night 2 Days. He also hosted the SBS talk show Strong Heart from 2009 to 2012. In 2017, he joined the SBS variety program Master in the House, which won him the Daesang at the 12th SBS Entertainment Awards and Best Male Variety Performer at the 57th Baeksang Arts Awards.

Lee Seung-gi enlisted for his mandatory military service in February 2016 and was discharged in October 2017. He was previously in a relationship with Yoon-ah of Girls’ Generation. In 2021, it was confirmed that he is dating actress Lee Da-in.