In 2009, 100% member Rockhyun - under his stage name Rocky (Hangul: 로키) - was one of the two members of Andy Lee's boy group Jumper (Hangul: 점퍼) that released two singles; "Yes!" featuring Eric of Shinhwa and "Dazzling" (Korean: 눈이 부셔) featuring Jiyoung of Kara.
The same year, Minwoo was featured during Andy's promotion for his song "Single Man", along with Jumper's second member Park Dongmin (Hangul: 박동민). Minwoo has also been active as an actor. He starred in KBS2's 2006 drama Sharp 3 (Korean: 반올림3), SBS's 2007 drama The King and I (Korean: 왕과 나) and in two movies, Crazy Waiting (Korean: 기다리다 미쳐) (2007) and Where Are You Going? (Korean: 특별시 사람들) (2009).
Between June and September 2012, 100% were featured in SBS MTV's variety show Teen Top Rising 100% (Korean: 틴탑의 뜬다 백퍼), in which they starred alongside fellow TOP Media artist Teen Top and their founder Andy Lee of (Shinhwa).
Their debut single album We, 100% was released on September 18. It consists of three tracks and one instrumental version, which were all written and produced by Super Changddai. The same day, the music video for its lead track "Bad Boy" (Korean: 나쁜놈) went online on the band's official YouTube channel. 100% made their live debut of "Bad Boy" on September 21, 2012 on KBS Music Bank, followed by MBC Music Core and SBS Inkigayo that same weekend.
On October 23, MBC held a press conference for 100% and Teen Top's second own variety program in Jangan-dong, Seoul. Teen Top & 100% Rising Brothers (Korean: 틴탑&백퍼센트의 떴다 브라더스) premiered on MBC Music three days later, showing the two music groups accomplishing missions.
On December 7, the music video for the digital single Guy Like Me (Korean: 나 같은 놈) was released. "Guy Like Me" was written by Minigun and Super Changddai, the latter of which had already written all the tracks on 100%'s first release We, 100%.
On May 23, the group's mini album Real 100%, along with its title track "Want U Back", was released.
On July 17, 2013 TOP Media announced 100%'s official fanclub as Perfection (퍼펙션). On November 14, TOP Media released information regarding the line-up; Rokhyun, Jonghwan, and Hyukjin along with rapper Chanyong, will be making a debut under the sub-unit named, 100% V. The group released a single album consisting of 3 tracks on November 20. The leading single was titled, 퇴근길 (Missing You). The group made their first live appearance on KBS Music Bank.
In February 2014, TOP Media announced on both 100%'s official website and facafe that leader Minwoo had to enlist in the Korean military starting on March 4. In March, the agency announced that Sanghoon will take some personal time off until he finalizes on what to do in the future. With five members remaining, 100% released both their second extended play Bang the Bush and music video for "심장이 뛴다 (Beat)" on March 17, 2014.
100% released both their third extended play Time Leap and music video for "지독하게 (Better Day)" on October 13, 2016.
100% debuted in Japan in January with the music video "How to Cry".Seo Minwoo (서민우)
Kim Rokhyun (김록현)
Jo Jonghwan (조종환)
Kim Chanyong (김찬용)
Jang Hyukjin (장혁진)
Woo Changbum (우창범)
Lee Sanghoon (이상훈)
ZEPP Tour - 100% X'mas Show
100% 2014 Japan Cool Live