4minute was formed in May 2009 and consists of Hyuna Kim (a former member of the Wonder Girls), Jihyun Nam, Gayoon Heo, Jiyoon Jeon and Sohyun Kwon.

On June 15, 2009, their debut single "Hot Issue" was released. "Hot Issue" was composed by hit song-makers Mr Shin Sa Dang Ho Raeng I and Mr Lee Chaekyu. The single's catchy and funky rhythm and melody caught on with fans and climbed up digital music charts such as Cyworld, Bugs, Soribada, and Mnet.

4minute held their debut performances on June 18-21, singing "Hot Issue" on Mnet M!Countdown, KBS Music Bank, MBC Music Core and SBS Popular Music show. They won the digital music award "Rookie Of The Month" for June and August. 4minute also won their first ever number one award on Inkigayo on September 27 and on M!Countdown on October 1.

At the end of August, 4minute released a mini-album called For Muzik containing 7 songs. The single "Muzik" draws on musical influences and sounds made popular in trendy European clubs.