Arsenal supporter Ryder faced fellow Brit Zach Parker on Saturday night at the O2 Arena in London.
The dangling carrot for the winner was the prospect of fighting Canelo next, with plans in place for the pound-for-pound great to fight in the UK for the first time.
Parker suffered a suspected broken hand in the early rounds and had to pull out before the fifth round got underway so Ryder was ruled the winner by TKO.
Hearn reacted to his fighter's win following Dillian Whyte's comeback victory over Jermaine Franklin.
The Matchroom promoter thinks Ryder "deserves" an opportunity to fight Canelo next.
"I am so pleased for John Ryder. Since he beat Daniel Jacobs, we've been looking for this big fight," Hearn told Matchroom boxing.
"We didn't expect it to be Zach Parker. He came through and was just too much for Parker, who I think had an injured hand. But he was getting to him and I think he would have stopped him anyway.
"I've already texted Eddy Reynoso (Canelo Alvarez's trainer) to say 'John Ryder is mandatory, let's go in May at the Emirates'. It would be a dream for Ryder, he deserves it.
"He is a very good fighter and he's the mandatory challenger for Canelo Alvarez. This could be our chance to bring Canelo to the UK, it would be unbelievable. We'll see if we can get it over the line."
Hearn then was videoed on facetime with Ryder. He added: "Unbelievable, well done mate.
"I've already put the text to Reynoso. Don't worry, it's got to be The Emirates, right?
"Is Wembley okay, can it be Tottenham stadium, or is that going to cause you a few problems? It's John Ryder vs Canelo Alvarez in London."
Ryder admitted following his win over Parker that "it would be a dream to fight Canelo".
"I want the big guns now. I want the Canelo fight. In this career that's the icing on the cake," Ryder said.
"I'm standing pretty now. It would be a dream to fight Canelo, on Cinco de Mayo, whenever, wherever.
"Whether it be fighting Canelo or being upgraded to full champion so be it. There are still great fights out there for me."