The Team Shoe-Box fighter impressed as he secured a unanimous points victory over Metcalf, who was performing his his home town of Liverpool.
It was a crucial fight for both boxers, as they were coming off rare defeats.
Conway had lost his WBA Inter-Continental title to Souleymane Cissokho in Texas in May, while Metcalf had lost a British title fight with Ted Cheeseman in Gibraltar.
It was the 33-year-old's first professional defeat, while Conway's was his first in a bout of more than three rounds, his only previous loss coming in the final of the Ultimate Boxxer competition in 2019.
Hearn had praised both fighters before the fight for taking on such a high-risk encounter, with a second straight defeat going to be a serious setback for the career of the loser.
The Matchroom supremo felt Conway was a deserved winner of the 10-round contest, and is now backing the Northampton man to take on another high-profile match-up next.
"The fight didn't really catch fire, but it closed out well and was exciting towards the end," said Hearn.
"Neither guy really took control of the fight, but I felt that Kieron did win the fight and it was a big one for him, to come off the back of that Cissokho defeat and get a win.
"He came to do that in Metcalf's back yard as well, so props to him and now he will move forward."
There are going to be several options now open to Conway, who has made it clear he will be willing to take on any challenge offered to him.
One of the options Hearn believes could work is a rematch with Ted Cheeseman - the pair drew their previous encounter in the summer of 2019 - but he lost his British title to Troy Williamson later on the same bill as Conway on Saturday.
Asked what could be on the cards next for Conway, Hearn said: "It could be a Ted Cheeseman re-match.
"It could also be an Anthony Fowler fight, a Scott Fitzgerald fight, as he has put himself right back in the mix."