Despite the fact that the fight went the distance, DeGale was the dominant force over the 12-round contest.
The judges scored the bout accordingly, with a 115-113 and two 117-111 cards to confirm a unanimous points decision victory for the Brit.
However, despite extending his winning record to 23-1, DeGale was disappointed that he could not knock-out his Mexican opponent.
"He's a very tough fighter, he has obviously got a lot stronger and better over the last year and a half," DeGale told Sky Sports News.
"I should be taking out people like Medina, that's no disrespect to him. But I'm still learning. The main thing is I am still champ. I've got to work on things still."
The 30-year-old also stated that he now wants a unification battle with Badou Jack.