The 18-year-old joins The Tykes on a three-month loan deal in a bid to gain regular first-team football after spending much of his time in England with The Gunners' youth and reserve teams.
Arsene Wenger paid £350,000 for Mannone's services last summer after he impressed for Atalanta and the French tactician is thought to rate the keeper highly.
Mannone made seven appearances for the club's reserves last season and was also a regular in Arsenal's Under-18 side, but will be hoping to make the step-up to senior football this season.
Barnsley boss Andy Ritchie is expected to install Mannone as his number two and is hoping the Desio-born goalkeeper can challenge first-choice Nick Colgan for a starting place.
Mannone is expected to be in The Tykes' squad for the visit of Southampton on Saturday.