Gabbiadini is the second professional player in Serie A - after Juventus and Italy defender Daniele Rugani - to contract COVID-19.
"UC Sampdoria announces that Manolo Gabbiadini has tested positive for coronavirus (COVID-19)," a club statement read.
"Gabbiadini has a slight fever but is otherwise fine. The club is activating all isolation procedures as set out by the authorities."
In a post on Twitter, Gabbiadini wrote: "I've tested positive for coronavirus. I want to thank you all for the many messages I've received. I also want to let you know that I'm fine, so don't worry. Follow the rules, stay at home and everything will work out."
"I've tested positive for coronavirus. I want to thank you all for the many messages I've received. I also want to let you know that I'm fine, so don't worry. Follow the rules, stay at home and everything will work out." https://t.co/w2UU3cwsN4— Sampdoria English (@sampdoria_en) March 12, 2020
Gabbiadini played 61 minutes of Sampdoria's 2-1 triumph over Hellas Verona on Sunday, a match that was ordered to be played behind closed doors.
Following the news of the former Southampton player's positive test, Verona cancelled all upcoming activities.
"Hellas Verona FC announces that, following the Sampdoria statement regarding Manolo Gabbiadini's positive test for COVID-19, any scheduled competitive activity is suspended until further notice," a statement from the club read.
"The club is taking steps to prepare all the necessary procedures."
The Italian government has suspended all sport until April 3 due to the outbreak of the virus and placed the country in lockdown, with all shops except food stores and pharmacies closing.
There have been over 12,000 confirmed cases of coronavirus and 827 deaths in Italy.