McCann 73, who sold his interest in Celtic in 1999 five years after taking over the club, married his wife Elspeth, 53, a year after coming from Canada to take Celtic from the brink of financial ruin to economic stability.
A joint statement from the McCanns issued to The Herald last night said: "As with many couples our lives have grown in different directions and both feel it is best we pursue separate lives.
"We parted amicably but will always be joined through our wonderful children of whom we are both so proud and thankful. They are turning out to be lovely people as they enter their adult years."
The couple, who moved to the US in 1999 after McCann sold his shares in Celtic, have three children: Ishbel, 18, Juliet, 17, and Malcolm, 15.
Mrs McCann said: "We have been living apart for some time now and we both felt that it is best to go in our own separate ways. But of course our contact continues, mainly around the growth and happiness of Ishbel, Juliet and Malcolm.
"I will always be grateful that together we have brought up three lovely children and their welfare will continue to be our shared priority as their lives develop."
Mr McCann said: "We both felt this was the right thing to do and I wish Elspeth every happiness for the future. We share a great love of our wonderful children and will look to support them as they make their way in life."
No other party is involved in the separation.
Mr McCann, who is now devoting his energies to his charitable foundation, came to the rescue of Celtic in 1994 when the club was within minutes of financial ruin.
An expatriate Scot living in Canada, Mr McCann had built his fortune on a golf holiday business that showed his skills as an expert in direct marketing to best advantage.
He acted as a guarantor for the club's £7m debt, injected additional finance, floated the club on the London Stock Exchange as a public limited company, Celtic plc, in order to raise capital from a share issue, and oversaw an extensive redevelopment of Celtic Park.
His legacy includes a financially stable football club and the redeveloped Celtic Park.
In 1999, Mr McCann sold his shares, with Dermot Desmond, the Irish businessman, becoming the largest single shareholder. Mr McCann, though, has remained a Celtic supporter and last month wrote to lapsed season ticket holders urging them to renew their subscriptions.
He will also unfurl the SPFL Premiership flag when he returns to Celtic Park for the club's first domestic home game.
"I am looking forward to that," he said last night. "It will be good to meet up with all the people I worked with and be introduced to the directors who came on the board after I left."
He paid particular tribute to Mr Desmond for investing in the club. "He put in £4m at the very beginning when he hardly knew me," said Mr McCann.
"He has invested substantially in Celtic over the years." He also praised Neil Lennon's tenure at the club as Celtic manager that finished at the end of last season, saying the Northern Irishman had overcome "extraordinary circumstances".
Mr McCann also explained why he could not attend a home match in March on the 20th anniversary of his takeover.
"I had just had an operation and was about to be called as a witness in a court case so it was impossible," he said.