The former England coach had a ill-fated and short-lived period as boss at the City Ground, holding the position for only 111 days before handing in his resignation.
McClaren has been frustrated by the club’s lack of available transfer funds, something he claims he was promised before joining the Championship team.
With the Midlands outfit in trouble after a slow start to the campaign, McClaren pressed the issue of financial backing once more after the side’s heavy defeat to Burnley on Tuesday.
With no further commitment to new players come January, McClaren has confirmed that he has left Forest.
“I resigned. They don’t share the ambition that I came for,” he angrily told reporters on Sunday.
The news was confirmed on the club’s official website, with the search for a new man in place already.
“Steve McClaren has resigned as manager. He has left the club without compensation — nor will he be seeking any. The club can confirm that the search for a new manager will begin immediately,” the statements reads.
McClaren recorded only two wins in his ten games in charge, and will now look for a new coaching role, potentially back in Europe after successful spells at FC Twente and Wolfsburg.
The manager’s complaints were with chairman John Doughty, who will also be leaving Forest in the near future.
“Mr Doughty will step down as chairman at the end of the season. The search for a new chairman will commence immediately,” the Forest statement concluded.
By Gareth McKnight