McGuinness, a qualified sports psychologist, will spend two days a week at Celtic's Lennoxtown complex motivating the club's young players and will be available to the first team if Neil Lennon requests his skills.
The Donegal boss believes that being immersed in a professional atmosphere can only enhance his skill set, which will ultimately benefit Donegal, where he is about to begin the third year of his four-year contract.
"It's a great opportunity for myself personally, in terms of my own development," he said
"I suppose it's a great opportunity for Donegal, on a level, because I'm working in a professional environment a number of days a week and that's going to be a great environment for me to be in terms of the skills I'm going to learn at Celtic to bring back to Donegal.
"It's going to be great. It's the best of both worlds. For your day job to be in sport and for the passion for Donegal still to be in-situ.
"I have to be very, very thankful to Celtic Football Club for that and giving me the opportunity to (combine the roles). They've been very fair in terms of my own role with Donegal.
"They've given me the opportunity to stay on with Donegal and participate in all the training sessions and be at home for all the training sessions.
"That flexibility made the decision a lot easier for me.
"I'd have to be very thankful to the football club and to (Celtic manager) Neil Lennon."
Celtic boss Lennon was quick to point out that the Bhoys do not wish to prise McGuinness away from his role with the Tír Conaill Men.
"We're delighted to have brought him in and I think he's pleased about it as well," Lennon said.
"We didn't want it to ruin or affect what he has been doing with the Donegal team because they have been magnificent.
"It will have no effect on what he is doing at Donegal."
McGuinness insisted that taking up the role at Parkhead won't have an adverse affect on the Donegal team.
"I've sat down and I've worked it out. There will be no drop-off in terms of my own attendance at training and my input to the team," he added.
"We've been on a great journey for the past two years.
"Obviously, I think the world of them, they've been great to work with.
"It would have been very difficult to walk away from them so I'm delighted that I don't have to do that."
Lennon revealed that Celtic's majority shareholder Dermot Desmond was behind the intriguing recruitment of McGuinness as performance consultant.
Hoops boss Lennon, speaking ahead of tomorrow's Scottish Premier League clash with St Johnstone at Parkhead, said: "Dermot made me aware of Jim's position and made the introduction.
"We had a long conversation about both sports and sport in general and there is stuff I can learn from him (Jim) and there is stuff he can learn from us so it is a win-win situation.
"Jim has a skill set that we don't have here, in terms of the psychological side of the game. It is a huge part of sport.
"He will player profile the younger players, look at their strengths and weaknesses, study their background and their state of mind.
"He will not be able to coach, he is not a qualified football coach but he does know sport and has excelled in his own sport.
"So the transition to football will not be a problem.
"He will predominantly work with younger players.
"But if I feel there is a first-team player that would benefit from Jim's skill I would have no hesitation in using him.
"He will probably initially come in two days per week and we will take it from there."
McGuinness, who has a masters degree in sports psychology, was a guest of the Glasgow giants at Wednesday's Champions League win over Barcelona, having viewed the club's facilities in a previous visit.
The Glenties man will combine his Celtic role and the Donegal job with his assistant, Rory Gallagher, taking on increased responsibilities.
McGuinness' role in bringing Donegal from a mediocre outfit to two-time Ulster winners and All-Ireland champions has been hailed as one of the greatest management feats in GAA history.
The manager's attention to detail led to a defensive playing system which led to widespread criticism in his first season in charge, but the Donegal team employed a more attacking method this season as they clinched the county's second All-Ireland triumph.