The 41-year-old was recently named the PFA Scotland manager of the year after leading St Mirren to the Championship title in emphatic fashion.
That came after securing an improbable escape from relegation in 2016-17 and he will arrive on Wearside as one of the highest-rated managers north of the border.
The deal is likely to be completed today after a dramatic 24 hours in which St Mirren chairman Graham Scott lashed out at reports that terms had been agreed.
He accused Sunderland of ‘skulduggery’, but a club statement later confirmed that they had granted permission for talks to take place.
Man in life-threatening condition after 'serious collision' involving car and pedestrian in South Shields
Campaigners rally against Local Plan after farmland in Cleadon earmarked for 156 homes
Pair set up cannabis farm in town centre flat
South Shields man jailed for terrifying physical and sexual assault on woman in her own home
Appeal to find owner of lost Labrador after dog found near Jarrow Cemetery
He said: “St Mirren Football Club can confirm we received a formal approach from Sunderland AFC for permission to speak to our manager, Jack Ross.
“After agreeing to our terms, we have reluctantly given them permission to speak to Jack about their vacant manager’s position.”
Sunderland owner Stewart Donald told fans on twitter that a deal was nigh.
He wrote: “I said in the press conference we would hopefully have our man by the weekend.
“The update is we have agreed terms & as I said it is with the legals now.
“By close of play tomorrow I would hope to make an announcement. All on course.”
Donald told talkSPORT that he had agreed a two-year deal with the new manager, while not naming him, with an option of an extra year based on performance.
Donald confirmed at his first press conference on Wearside that the new manager would have full control over recruitment and would be charged with transforming the culture of the club.
He said: “The manager will recruit the players – that will be his call. We have a recruitment team and there will still be a recruitment team who works with him, but there will be no interference from Charlie [Methven] or I.
“It needs a cultural change. The standards have got to be really high when you go round the Academy of Light.
“If you’re a young footballer, or any kind of footballer, and you wander in there as a League One footballer, we’ve got to make sure people don’t think they’ve arrived and all their hard work is done.
“The standards that the football club should set, should be absolutely top drawer, it should be 100 per cent effort.
“They’ve got to get the culture, they’ve got to work hard, they’ve got to do everything right, and the manager has to set the tone for that.
“He cannot be somebody that will let them off with anything.
“If we want to win anything, especially now in League One, this will be the place where everybody, as soon as the fixtures are drawn out, (will ask) when are we playing Sunderland?
“They will come up here and, when we go there, it will be a big game.
“You are going to have to be strong and, if you are going to be that, the manager has to set the tone, so I am expecting to bring someone in who sets the standard right at the top and then make sure that the players understand what is expected of them, and get the right type of characters here.”