Cahill and Boyata both worked for Coyle at Bolton Wanderers, before the former was sold to Chelsea for £7 million.
And the coach, currently working in MLS, feels Boyata can emulate the England centre-back with Celtic.
Indeed, at 24, Coyle thinks the defender can still come on leaps and bounds at this stage in his career, while also heaping praise on the form he showed at Bolton.
It was his form that made Coyle confident enough to sell Cahill to Chelsea and he sees plenty of potential in the man Celtic have signed after he was allowed to leave Manchester City.
The former Burnley and Bolton boss said: "Dedryck is still capable of a fantastic career in football. He will be a good signing for Celtic. He will be good for them and they will be good for him.
"I brought him into Bolton and he played six games and did really well, and even scored against Chelsea, but picked up an injury. I had originally got him as cover because I thought we might lose Gary Cahill in the previous transfer window but Dedryck played alongside Gary and did well and then we sold Gary to Chelsea in the January window for £7m.
"Dedryck has not played a lot of games but there is still plenty of time. Cahill didn't get full established until he was 23 and centre-backs are definitely better with age."
Plenty has been made (with Coyle also discussing it) of Boyata's ability to play out from the back, something boss Ronny Deila wanted in the absence of Jason Denayer, who has returned to Manchester City after his season-long loan spell finished at Celtic.
Do you think the 24-year-old will be a hit at Parkhead?