In 2012, Bang partnered with fellow MBLAQ member G.O, with whom he had collaborated previously for drama soundtracks. In May of that year they released a single, "Wild," for MBLAQ's Asia tour in June, without a name and their debut was eventually postponed.
Bang appeared in South Korean variety shows, with the other MBLAQ members and on his own, and performed various songs by other artists. He wrote the lyrics to two of MBLAQ's songs, "You're My +" and "Can't Come Back."
In 2013, Bang joined Korean military variety show Real Men briefly and attracted much attention from the public. In July of the same year, Bang and his fellow MBLAQ members made a comeback after over a year's absence with the mini album "Sexy Beat". It was also revealed that Bang participated in the production of the mini album. He wrote the lyrics of "R U Ok?" and "Girl". On December 24, Bang released his first digital single "Come On", which was revealed earlier in MBLAQ's Global Sensation Tour 2013, in which he had took part in the production.