Two judges scored the fight 30-27 and 29-28 for Griffin. The third judge had Ortiz winning 29-28.
The two former light heavyweight champions fought to a controversial split decision in 2006, with Ortiz getting the victory. The rematch was another close call and similar to the first fight as Ortiz started strong before Griffin rallied to take control.
"It was a great fight," Griffin said. "It's tied 1-1. I think we should do it again."
Both fighters exchanged blows throughout the first two rounds in a back-and-forth bout. Ortiz was able to take Griffin down to the mat multiple times and opened a cut under his left eye, but Griffin got the better of the stand-up and took over in the third and final round.
Griffin landed multiple kicks and punches to Ortiz and dominated the third round.
"Forrest came with a lot of heart. He put on a great show," Ortiz said. "Forrest is the better man tonight. I give it up to him."
"I am the number one contender in this weight division," Koscheck said. "I thought the fight went well, and I want to fight whoever they put in front of me."
Dan Hardy will fight Georges St-Pierre for the welterweight title, and Koscheck could face the winner of that bout.