After being officially announced on January 28, 2010, The Boss debuted on March 4, 2010, with the song "Admiring Boy" on Mnet M!Countdown.
After the last member from the original lineup, Kevin, left the band, he was replaced by Karam and Injun.
The Boss appeared in a live Japanese variety show called Made in BS Japan as Monday special MCs.
Made in BS Japan is a television show that introduces Pan-Asian food, fashion, and history.
In January 2011, they returned to the music scene with a 3-member unit group named Popsicle with members Mika, Karam, and Jay.
On March 30, The Boss released their first Japanese singles' PV: "Love Power".
The Boss made new songs for their Japanese debut instead of using translated versions of their Korean releases as other groups did.
The Boss also gathered 30,000 fans for their Love Parade event held in Sapporo, Fukuoka, Nagoya, Osaka, and Kanagawa.
[6] In September, after almost one year in Japan, The Boss returned to South Korea to promote their second single album "Lady".
The single contained the ballad title track of the same name, an instrumental version of the song, and "Calling You".
"Lady" overtook Girls' Generation's The Boys for second in Korean sales in Japan at that time.
"Love Days" also reached 4th on USEN’s K-Pop's Weekly Chart on December 28.
With the arrest of their company's CEO Jang Seok-woo for sexual harassment on April 10[8] and his subsequent detention in police custody three days later, the group cancelled the planned released of their first Korean album, Shadow.
Breaking their two-year hiatus in Korea, POOM Entertainment stated that The Boss had signed a contract with them and would be releasing an album in November.
After signing with XING, they promoted extensively in Japan, holding concerts and fan meetings almost every month.
[10] In 2023, The Boss appeared on Peak Time, a show promoting already-debuted K-pop boy bands, but withdrew before the second elimination round following pictures of Karam partying with Japanese AV actors being published on various online communities.