The former England boss was sacked by the Premier League strugglers on Friday, with the Magpies 19th and one point from safety.
McClaren’s last game in charge was a home defeat to Bournemouth, with the writing on the wall in the aftermath of the loss.
The 54-year-old took training on Tuesday, Wednesday and Thursday before he was replaced by Rafa Benitez on Friday.
His position became untenable with his 28 league games bringing just six wins and 24 points despite an investment in the playing staff in excess of £82million.
However, he remained insistent that he would have kept the club up given the opportunity.
In a statement released through the League Managers’ Association, McClaren said: “I am obviously very disappointed with the decision.
“I appreciate any frustrations relating to the team’s results and the club subsequently finding itself in a battle to avoid relegation. I remain confident, however, that we would have stayed in the Premier League with a view to building for next season.
“Whilst there has been a lot of intense speculation surrounding my position over recent days, my sole priority has been to maintain my professionalism and carry on with my work to best prepare the team.
“I would like to place on record what a privilege it has been to manage Newcastle United Football Club. It is a great a club – the embodiment of the city, with incredible supporters.
“For every supporter of Newcastle United, I genuinely hope the club can produce the results I believe they are capable of, between now and the end of the season, to maintain their Premier League status.
“Newcastle United is a club that must build for the long term to deliver what the supporters deserve – success and silverware.”
Charnley paid tribute to McClaren’s dignity for the way he had handled a difficult situation.
He said: “I would like to thank Steve personally for his services to Newcastle United. He is a man of integrity and class and he has conducted himself with great dignity during this difficult time.”