The Republic of Ireland Under-21 skipper scored his first senior goal for the club in Saturday's 1-1 draw at Birmingham City.
Dublin-born 'Steo', 21, now has 27 appearances to his name having made his Premiership debut on Boxing Day 2003 - he might have played more this season but for some ill fortune with injuries.
Ledley, who also came through our youth ranks, insisted he knew straight away Stephen was up to the task in the top flight.
"He gets better and better," said skipper Ledley. "From his first game you could tell he had what it takes to be a player. The more games he's played the more he's improved.
"He's looking brilliant at the moment and he gets into some great positions from right-back. He showed a cool head at Birmingham and it was a great finish for the goal.
"Everyone was delighted for him. Steo's a great lad and he's played really well since he came into the squad. He's been unlucky a few times when he's got in this season through injury.
"He came up through the Academy and that's always great for the club."
Ledley King is delighted to see the continued progress of Stephen Kelly - not least because he's a fellow product of our Academy system.