It is understood the 39-year-old insisted any deal with the Scottish Premier League champions allowed him remain in charge of the All-Ireland champions.
After notable involvement by the club’s major shareholder Dermot Desmond, Celtic yesterday confirmed McGuinness has joined as a performance consultant.
McGuinness will take up the position within the Celtic’s academy at the end of the month but will divide his week between Donegal and Glasgow, initially working two days at the club’s training base in Lennoxtown.
It is believed Celtic had been keen for the Glenties man to take up a full-time role but McGuinness was determined that he be able to remain in his Donegal post, a role he was twice overlooked for.
McGuinness praised Celtic for understanding the extent of his commitments with Donegal as he faces into the third of a four-season term next season.
It had been suggested assistant manager Rory Gallagher may have to take one training session alone every week but McGuinness confirmed he won’t be absent from any.
“I have to be very, very thankful to Celtic Football Club for that, giving me the opportunity to do that,” he told Highland Radio.
“They have been very fair with me in terms of my own role with Donegal and they’ve given me the opportunity to participate and be at home for the Donegal training sessions.
“That flexibility has made the decision a lot easier and from that point of view I have to be very thankful to the football club and Neil Lennon, the manager.”
McGuinness said he has already worked out the logistics of commuting to and from Donegal to Glasgow with Lennon stating he will be in Glasgow initially two days a week.
“I’ll be at home for a number of days and then I’ll be over and back. If I go over for a day or two I’ll probably come back for training on a Thursday night and go back over again for a day or two and then return for training at the weekend.
“There’ll be no drop off in terms of my own attendance at training and the input I’ll be putting into the team.”
Lennon, who was at this year’s All-Ireland final as well as Donegal’s post-match function, described McGuinness’s appointment as “a win-win situation” for the pair.
“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 cross 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.
“It will have no effect on what he is doing at Donegal. He will probably initially come in two days per week and we’ll take it from there.”
Speculation about McGuinness’s future rose following his guest appearance at their Champions League game against Benfica in September.
He had also been in attendance for their qualifier game against Helsingborg the previous month where it’s believed initial talks with Lennon began after Desmond had introduced the pair.
However, the rumours about a move intensified this past week after he had been an official guest of the club’s once again for their thrilling group win over Barcelona on Wednesday.
Former Donegal footballer Martin McHugh, a close friend of McGuinness and father of All Star Mark, revealed Celtic chief Desmond had been impressed by the Donegal manager’s interviews on The Sunday Game.
He also hinted the county were fortunate to hang onto their manager. “Nobody would turn that down. Nobody in Donegal is going to say anything about that.
“The commitment and effort the man has given Donegal, it’s going to be a big commitment for him to stay on with Donegal.
“We have to look at his point of view that he has so much time for the players and everybody involved.
“He could have easily said ‘alright, I’ll move on’ but that just shows the commitment and passion he has for Donegal football.
“Knowing Jim McGuinness, he will do what’s right for Donegal football. Whatever decision he makes, Donegal football will be first in that decision.”
On Twitter, former player Kevin Cassidy, who McGuinness controversially dropped off the panel 12 months ago, congratulated his old manager on his new job.
However, he described it as a negative development for Donegal. The Gweedore man, a Celtic supporter, tweeted: “Welcome Jim to the best club and fans in the world although it’s a bad day for Donegal GAA it’s an opportunity 2 big to turn down #hailhail.”
McGuinness’s former Donegal boss Brian McEniff said he is capable of juggling the two roles but warned of the difficulties involved.
“If anyone can work it, Jim can work it,” McEniff told RTÉ Radio One. “And I’m sure he’s thought it before he went over.
“It’s not an instantaneous decision. He’s been over and back to Celtic Park since the start of August when he went over there to view the situation.
“And it was kept low profile, naturally enough here within the county, because we were looking at a bigger thing — winning an All-Ireland.
“But he’s made his bed now at this stage and I feel he has the capacity to do it. But it will take its toll.”
McEniff said the job couldn’t come at a better time for McGuinness.
“Initially my reaction would be I’m very happy for Jim because he had no job really at this particular point in time.
“His wife (Yvonne) has been reduced to three days a week and he has three children under the age of five.”