The 25-year-old, who spent the second part of last season on loan at Real Betis, passed a medical with the Spanish outfit on Tuesday evening.
"I'm delighted to be in a team that is always competing. I'm very happy to be here," Pabon told reporters at a press conference.
"I think I can adapt well to what the coach needs because I am a man with speed and movement and play on the back of defenders."
Pabon could make his debut in the league meeting with Barcelona at the weekend.