ECB chief leaves under cloud after controversial cancellation of Pakistan tour
Watmore only replaced Colin Graves as chairman in September of last year, meaning he is leaving his post after serving just over a year of a five-year term.
According to a report from the Times, the decision to scrap the trip to Pakistan ramped up the pressure on Watmore.
That was followed by a meeting with county chiefs last month which a source told the Times was a "shambles".
In a statement, the ECB confirmed the news, saying: "ECB Chair Ian Watmore is to step down with immediate effect, it has been announced today.
"He has reached a mutual agreement with the Board to stand down following the end of the domestic season and after helping to steer the game through the challenges of Covid over the past year.
"The decision follows a successful summer of domestic and international men’s and women’s cricket, the launch of The Hundred and record numbers playing the game recreationally."
However, Watmore has stated that his decision to step down is due to the "personal toll" the role has had on him.
He said: "It is with regret that I step down as Chair of the ECB, but I do so in mindfulness of my own wellbeing and that of the game which I love.
"I was appointed to the post in a pre-pandemic era, but Covid has meant the role and its demands on time are dramatically different to all our original expectations, which has taken a personal toll on me.
"Given this, the Board and I feel the ECB will be better served by a new Chair to take it forward post pandemic.
"Leaving now, at the end of the season, gives the Board time to find a new Chair to support cricket through the challenges of the 2022 season and beyond.
"On a personal level, I also retired last month after five years at the Civil Service Commission and recently became a grandfather. I would now like to retire completely from work and enjoy our great game as a spectator."
The ECB's Deputy Chair Barry O'Brien has now been appointed interim chairman and one of his first duties will be chairing a meeting on Friday where the organisation is expected to give the go ahead to this winter's Ashes tour.