Ray Wilkins has left Millwall after a spell as a consultant to the club.
Wilkins assisted both Dennis Wise and David Tuttle at Millwall
The former Lions assistant manager had returned to the New Den in March to help then boss David Tuttle - and was asked to stay on during the summer.
"At that time, we felt having someone of Ray's experience and knowledge would be a great advantage," chairman Stewart Till told the club website.
"It was always the intention on both sides that once the season was underway, Ray would leave us."
Till also insisted that they would not be rushing to appoint a new manager, a week after parting company with Nigel Spackman.
"The last two results have confirmed that with (caretaker boss) Willie Donachie in charge, the team are in good hands," he said.
"We would be more than happy if he continues to make a good case for being given the position on a permanent basis."