McGuinness, who last week led Donegal to their third provincial crown in four years, had been lured to Celtic Park by previous boss Neil Lennon after delivering the Sam Maguire in September 2012.
Lennon was convinced the Glenties man's 'skill-set' would work across both codes and new Celtic manager Ronny Deila required little time to be convinced of his worth to the side.
The Norwegian has promoted the 41-year-old to a consultancy role with the seniors and McGuinness is relishing the challenges ahead.
Speaking to Today with Sean O’Rourke on Irish radio, he said: “It’s been fantastic, a privilege.
"Most of my work was with the development squad, but now I have more of a role with the first-team.
“Ronny is keen on the psychological side of things. He is very driven by high performance and balancing that with high energy.
"He likes to keep his players positive and fresh and I'm looking forward to working with him."