Mr Mason took up the post in January last year following the resignation of Sir Gary Verity, the organisation’s first chief executive.
Mr Mason announced his own resignation yesterday and will leave the organisation on October 22.
Sir Gary resigned in March 2019 on health grounds amidst allegations about expenses spending and his behaviour towards staff.
Yesterday, Carl Les, the leader of North Yorkshire County Council and board member for Welcome to Yorkshire, said he was “disappointed” in Mr Mason’s decision to resign.
Coun Les said: “I’m disappointed that we’re losing him, but I understand he’s had a very attractive offer for a new job in the New Year which he would like to take up.
“In the meantime he was very instrumental in setting up a dementia cafe in lockdown and I understand he wants to spend a bit of time between leaving Welcome to Yorkshire and starting his new job to continue to set it up.
“I wish him well in the future and now the board will have to consider what to do to fill the gap.
“James isn’t going immediately and it gives us time to start looking for a replacement.”
Fellow board member Nicky Chance-Thompson, the chief caretaker of Halifax’s Piece Hall, tweeted: “James Mason has been a fantastic and inspirational CEO leading the organisation through some highly challenging times.
“I wish him all the best in his exciting new role (s) and will miss working with him.
“Never met anyone as passionate about our county.”
Fiona Gardham, owner of bed and breakfast The House at Hawes, said she felt Welcome to Yorkshire would be “poorer without him.”
She said: “No one could have worked harder to support businesses through the pandemic in the last 18 months.
“He brought a sense of stability, honesty, and integrity to the organisation.
“I hope the team he has built will take forward what he started for the continued good of Yorkshire tourism businesses.
“I can’t help but feel Welcome to Yorkshire and those that it serves will be poorer for his departure and am sad he could not have been persuaded to stay.
“But I wish him the very best of luck in his new role. I hope they know how lucky they are to have secured him.”
Neither Mr Mason nor Welcome to Yorkshire could confirm details of his new job offer to the Yorkshire Post yesterday.
Under his leadership, Welcome to Yorkshire launched a campaign to promote Yorkshire as the “walking capital of the world” and there had been hopes that a cultural festival intended to take place alongside the Tour de Yorkshire next year would still be able to go ahead despite the race’s cancellation.
It comes after two years of turmoil for the organisation sparked by the allegations made against Sir Gary Verity.
Independent inquiries ordered by Welcome to Yorkshire and completed before Mr Mason’s arrival found a lack of clear spending policies meant accountants were unable to determine whether almost £1m worth of expenses were “reasonable and proportionate”.
Sir Gary paid back £44,000 to Welcome to Yorkshire and a police investigation into the matter was closed in 2020 with a decision to take no further action.
A parallel investigation into the management culture at Welcome to Yorkshire found he had “fallen short” of the highest performance and leadership standards expected of a chief executive.
Mr Mason's tenure as chief executive of Welcome to Yorkshire has been marked with both financial difficulties and the disappointment of the cancellation of the Tour de Yorkshire.
Welcome to Yorkshire took a £500,000 loan from North Yorkshire County Council in September 2019 after coming close to being unable to pay staff.
The organisation put out a further plea to local councils for £1.4m in emergency funding in June 2020 after the pandemic further hit its finances.
In January this year, one year into taking over as chief executive, Mr Mason admitted the organisation had been “fire-fighting” as it made a wave of redundancies to cut £1m from its wage bill.
“It has taken a lot out of me,” he said.
Earlier this month, it was announced that the Tour de Yorkshire cycling race was being called off for the third year in a row following a failure to reach financial agreement on how much Yorkshire public sector bodies should pay to fund the event in 2022.