The X Factor runners up secured the deal with the label today.
The group, made up of Aston, JB, Marvin and Oritsé, had previously expressed concern about contractual obligations after taking part in the ITV1 competition.
"JLS are the best boy band to emerge from a TV talent show," Epic managing director Nick Raphael said.
"The band already have an incredible fan base, and I look forward to launching their recording career."
Other artists signed to the label include Lemar, Shakira and Scouting For Girls.