The Black Cats are set to win the race to sign the Sweden international midfielder after his contract with Birmingham expired.
A number of clubs were keen to secure Larsson's services, with Arsenal, Blackburn, Aston Villa and Fulham all understood to be keen.
But the 26-year-old has elected to join up again with Steve Bruce, having played under the Wearside boss during his time at the St Andrew's helm.
Svante Larsson stated that the majority of formalities over a deal for his son had been completed, with only the number of years on the terms to be agreed.
"Sunderland have been on really hard since January. Steve Bruce has done much to bring about a deal and been very active," Larsson senior told Sport Folket.
"Sebastian along the way pointed out Sunderland as a distinct possibility. We have turned every stone and weighed the pros and cons.
"[The] Parties agree on the economic conditions and what remains is to agree on the length of the contract.
"They want a little longer and we want less. But I think there will be no problems."