The La Liga leaders confirmed the arrival of the German-born former Ghana international in a statement, adding that the club also have an option to make the deal permanent for a fee of 8 million euros (£6.98 million).
Barcelona have been linked to a host of forwards during the winter transfer window as they seek experienced backup options for Luis Suarez. The club let youngster Munir El Haddadi join Sevilla at the start of the month after he refused the offer of a new contract at the Catalan club.
Moves for Cristhian Stuani of Girona and Los Angeles FC's Mexican international Carlos Vela were rebuffed, with Boateng emerging as a surprise target earlier on Monday in the Spanish press.
An attacking midfielder by trade, Boateng has operated as a forward for the midtable Serie A outfit during the first half of this season, scoring four times in 11 starts.
He spent the 2016-17 season in Spain with Canary Islands side Las Palmas, netting 10 goals in 28 La Liga appearances, and will be presented officially at a press conference on Tuesday afternoon.
(Reporting by Joseph Cassinelli; Editing by Hugh Lawson)
