The 27-year-old will reportedly fly to Italy on Thursday for a medical after an explosive start at Southampton eventually saw him fall behind Charlie Austin, Danny Ings, and Shane Long in the striking pecking order.
Gabbiadini previously represented the Genoa club for one-and-a-half seasons before finding his way to Southampton by way of a two-year stint with Napoli.
The Italian scored six times in his opening four matches for the Saints, including a brace in an unfortunate League Cup final loss to Manchester United. He was signed by Claude Puel in January 2017 and played his final game for the club on Dec. 8 - new manager Ralph Hasenhuttl's first match at the Southampton helm.
Overall, Gabbiadini counts 10 goals in 51 Premier League outings.
The striker wasn't short of potential destinations but chose to rejoin Sampdoria, according to Hytner. Marco Giampaolo's side is currently seventh in Serie A, only three points adrift of the four spots that guarantee qualification for the Champions League.