Nicknamed God of Vocals, he is well known for his ballads, smooth singing voice, and ability to hit high notes without difficulty.

[1][2] Kim recorded a number of hit ballads with the South Korean band, Toy, in the mid-to-late 1990s, gathering a sizable cult following.

In 2011, Kim achieved widespread fame and recognition in South Korea through his participation on I Am a Singer, along with numerous appearances on variety and entertainment shows.

After completing his military service in the Air Force, Kim Yeon-woo participated in the 7th Annual Yoo Jae-ha Music Competition and won the gold prize.

Kim's popularity started to rise, and he gained widespread recognition from the public, earning the nickname God of Vocals.

[citation needed] Several K-pop idols such as B1A4's Sandeul, Shinee's Onew, and VIXX's Ken have mentioned Kim as their role model.