Wolves' Bakary Sako has revealed he is mulling over offers from the Premier League but is yet to decide on his future.
Rotherham boss Steve Evans will decide the fate of his out-of-contract players in a meeting on Monday.
The 29-year-old arrived on Wearside in January as manager Gus Poyet invested £3.2m in his services in the search for goals to keep Sunderland in the Premier League.
Although Sunderland avoided relegation, Scocco made only eight appearances and failed to find the back of the net.
His former club have been on his trail for several weeks and on Wednesday night concluded the deal.
"First of all, a fan of Newell's...welcome @nachoscocco32," the Argentinian club stated on social media.