김원주 (2F) – Fall again
Track 02 from Single "SPRING"
Release Date: 2020.04.17
김원주 (2F) – 열두 달이 봄 같애 (Feat. MC몽)
Track 01 from Single "SPRING"
Release Date: 2020.04.17
김원주 (2F) – Remember (With 벤 Of 베베미뇽)
Track 04 from EP "겨울연가"
Release Date: 2011.12.29
김원주 (2F) – 사랑하기 (With 세리 Of 달샤벳)
Track 03 from EP "겨울연가"
Release Date: 2011.12.29
김원주 (2F) – 겨울연가 (Feat. 美) (부제 ‘겨울이야’)
Track 02 from EP "겨울연가"
Release Date: 2011.12.29
김원주 (2F) – 단 하루만 더
Track 01 from Single "포맨 솔로 프로젝트 #2 김원주"
Release Date: 2013.10.07
김원주 (2F), 벤 – The Last Time
Track 02 from EP "The Serenade Part 1"
Release Date: 2013.10.24
김원주 (2F), 벤 – Baby Baby
Track 01 from EP "The Serenade Part 1"
Release Date: 2013.10.24
김원주 (2F) – Beautiful Day
Track 01 from EP "무한동력 OST Part 2"
Release Date: 2013.12.05
벤, 김원주 (2F) – 첫날밤
Track 01 from Single "첫날밤"
Release Date: 2018.07.26
김원주 (2F) – Wedding
Track 01 from Single "Wedding"
Release Date: 2019.09.29
전지윤 (JENYER), 김원주 (2F) – 아름다운 이별 (내맘을 들었다 놨다 인형뽑기, 누르면 나옵니다 노래자판기)
Track 01 from Single "복면가왕 131회"
Release Date: 2017.12.10
신용재 (2F), 김원주 (2F) – 하루 이틀 매일
Track 08 from Album "Dear"
Release Date: 2020.07.01