Khan, who won silver in Athens, knows Campbell from their time on the amateur circuit and is confident that the Hull boxer will come out on top.
"I've been very impressed with Luke and he's looked good on his way to the Olympic final," said Khan.
"I said at the start of the tournament that the two boxers who'd win gold from Britain would be Luke Campbell and Anthony Ogogo (who is guaranteed bronze after a semi-final loss)."
Irishman Nevin is also highly-rated, and has faced Campbell twice before with the both men having one win apiece.
Khan continued: "John Joe is a good fighter, he's a scrapper, but Luke has the boxing ability to win. Luke can fight at angles, hit and move, and has all the shots.
"They've met before and Luke won in the World Championship semis, I can't see anything but the same result here and Luke winning gold."
The final will take place at the Excel Arena in London, at 8.45pm tonight.