It's believed Humphrey's position was discussed at a Thursday night board meeting, and the circumstances of his exit will be addressed again next week.
"The Board of the Manly Warringah Sea Eagles has accepted the resignation of Chief Executive Officer Stephen Humphreys, effective immediately," Manly said in a statement on Friday afternoon.
"The resignation comes after discussions with the Board."
Sea Eagles director and part-owner Gary Wolman has been appointed interim CEO while recruitment for a permanent replacement is underway.
Humphrey's exit marks the end of his second tenure in charge of an NRL club, having previously presided over Wests Tigers between 2009 and 2013.
The son of former NSWRL boss Kevin Humphreys, his appointment in 2019 came after years of high turnover in the top Manly job.
While Humphreys was there Manly managed to fight off rivals to re-sign Origin star brothers Tom and Jake Trbojevic, and coach Des Hasler took up an extension to his contract last year with key performance requirements.
Manly only this week opened the new Bob Fulton Stand and Centre of Excellence, and appeared to be on the verge of securing funding for a makeover of Brookvale Oval.
Now, they are back in a familiar spot with a part-owner acting as an interim CEO and looking for a new chief executive.
David Perry held the position of general manager from 2011 to 2014, before being ousted as part of an ownership battle at the NRL club.
He was replaced by CEO Joe Kelly, who stepped down in 2016.
Former school principal Tim Cleary then lasted just five months in the role before losing out in a power struggle to Bob Fulton, before former Cronulla boss Lyall Gorman took charge.
Gorman was later moved onto another role before Humphreys took charge at the end of the 2019 season, with the club becoming a genuine premiership contender again last year.
11°C