The winger has been told by Middlesbrough that he can cut short his season-long loan deal after struggling for game time this season. Roberts spent three years at the Hoops across two different loan spells and was a huge fans' favourite.
Ferry told the Go Radio Football Show: "I think it'd be a no-brainer.
"Celtic have missed that sort of magic on the wings this year.
"When teams sit in against them, it usually goes wide then back into the middle, whereas with Patrick Roberts you know that if he gets the ball he's only going to go at his full-back.
"I think as many of those players that Celtic can get the better.
"I think he's struggled anywhere he's been. The one place that he's found form is Celtic so for me, it would be a no-brainer for both parties."