Pearson recently joined the Owls as part of their news sporting structure, but has now taken up a similar role up the M1 at Leeds.
The former Hull FC owner and Leeds director was less than a month into his post at Hillsborough - as part of a three-man sporting committee along with Glenn Roeder and head coach Stuart Gray, having been appointed on April 20.
Pearson’s major role was to advise Chansiri on business strategies, with the Owls now faced with replacing him at short notice.
Part of Pearson’s remit was to also deal with agents and rival clubs regarding transfers.
Chansiri said: “In many ways Adam’s departure underlines the strength of his appointment.
“These things happen in every line of business and football is no different.
“I wish Adam well for the future and look forward to welcoming him to Hillsborough next season.”