According to reports, Prince Boateng, 31, will join Barca until the summer with the option of making the move permanent. "His ability to bring people into the game means he is excellent at playing behind the main striker".
Speaking to Sky Sport Italia, Boateng said: "It's a bit of a sad day, because I leave a fantastic group and a club like Sassuolo that gave me so much".
Barcelona relased a statement along with a video, boasting Boateng's achievements.
Reliable Italian journalist Gianluca Di Marzio confirmed that Boateng is in advanced talks to sign for Barcelona, with Sassuolo CEO Giovanni Carnevali flying to Spain on Monday afternoon to finalise negotiations.
"I've got a lot of respect for this side and that is why I had to say my goodbyes in person".
Barca head coach Ernesto Valverde has been looking for attacking reinforcements as cover for Lionel Messi, Luis Suarez and Ousmane Dembele - the latter now facing two weeks on the sidelines with a sprained left ankle.
A number of options were looked at but ruled out for various reasons.
German-born Ghanian Boateng is now with Serie A side Sassuolo, having moved last summer from German club Eintracht Frankfurt.
Boateng's arrival at the Nou Camp marks his return to La Liga, after featuring for Las Palmas in the 2016/17 season where he scored 10 goals in 28 appearances. Denis Suarez, despite Valverde's reluctance to let him go, is still keen on a move to Arsenal, while the club are open to offers for Brazil forward Malcom.