NEIL Harris said it was the "right decision at the right" time to step down as manager of a "uniquely wonderful football club".
Harris left Millwall on Thursday after four-and-a-half seasons in charge that included promotion to the Championship and two FA Cup quarter-finals.
Harris released a statement through the League Mangers Association.
He said: "After 17 fantastic seasons as player, coach and manager, at a uniquely wonderful football club, yesterday, I decided to inform the board of my decision to step down from my position at Millwall Football Club. It is not a decision that was made with haste. However, I believe it to be the right decision at the right time, not only for the club, but for me and my family also.
"I truly believe that I leave the club in a very healthy position in terms of infrastructure, staffing and playing squad which gives a new manager a platform to continue the club's development.
"During the last four and a half years as manager, there have been some incredible successes for our club, including two Wembley play-off finals, a promotion back to the Championship, two FA Cup quarter-finals, and now, relative stability in the second tier of England's very competitive league structure.
"Throughout this journey, I have been fortunate to have been supported by a very hard-working staff, none more pivotal than David Livermore who leaves with me. Also, a group of players whom I respect and have enjoyed coaching every day.
"I'd like to say a huge thank you to the chairman John Berylson and the board of directors, not only for the opportunity to manage a club I love, but also for their unwavering support and guidance at all times.
"And lastly, to the heartbeat of the club, the very loyal fan base that supported my team up and down the country. I hope I've repaid your trust in me with a lot of happy memories.
"I look forward to coming back to The Den to see so many good friends in future."
Image: Millwall FC