Campbell previously had a one-year spell at Betis back in 2012/13 and he was not involved for Arsenal this season because of a knee injury he picked up on international duty.
This move is the sixth time the 25-year-old has left Arsenal on loan, with stints at FC Lorient, Betis, Olympiakos, Villarreal and Sporting Lisbon.
There is no option to make the deal permanent after the loan deal expires.