Ralph Topping, who stepped down as chief executive of William Hill last week, will reportedly become one of the most prominent business leaders so far to back a Yes vote in next month’s referendum.
Sky News said he will argue that pro-union campaigners have been guilty of “political posturing” whose arguments lack economic logic.
Mr Topping began his career as a Glasgow bookmaker and commuted to William Hill’s head office from his home in Scotland until he stepped down on 31 July.
He will reportedly argue that Scotland’s largest financial institutions would be unlikely to move their headquarters south of the Border if there was a vote in favour of independence.
Mr Topping, who is also a director of the Scottish Football Association, is understood not to be a member of any political party.
Sky said it understood that William Hill was keen for Mr Topping to delay making his views public until he left.
The news came as Campaigners for the Union were accused of “scaremongering” over the impact of independence on Scotland’s financial sector, with former RBS boss Sir George Mathewson, insisting this would be “an opportunity, not a threat”.
Sir George said those who argued against a currency union “ignore the interconnected nature of our financial systems”.
He said: “As the debate enters its final stage, careful analysis is giving the lie to the Unionists’ scaremongering about the consequences of independence.