It is believed the deal is worth €18m plus a further €2m in performance-related bonuses. The contract is thought to include €3m per season wages.
Southampton FC announced this evening that Osvaldo has signed a four-year contract and will meet the media tomorrow.
“Saints are delighted to announce the signing of Italy international striker Pablo Daniel Osvaldo from AS Roma.
“Osvaldo has agreed a four-year deal at St Mary's, and will be officially presented as a Saints player tomorrow.”