The Arsenal striker, who is yet to receive a work permit to play in England, is currently on a season-long loan deal with the La Liga outfit.
Campbell has said that he is enjoying life in Spain and that he would like to remain with the club, who are in contention for a place in the Europa League.
"I feel very comfortable and have identified with the team and people of Betis," he told eldesmarque.es.
"I love the city, and if I have to stay I am available. Hopefully we will be in Europe too."
Campbell has scored two goals in 18 appearances for Betis.