Boateng, 31, joined the LaLiga giant on loan from Serie A side Sassuolo for the rest of the season, with an €8million purchase option included.
The former AC Milan and Tottenham midfielder said it was a dream to get an opportunity to play for Barca.
"I'm very happy. It's a big honour to be here and have the possibility to play for this great club," Boateng told Barca TV.
"For every kid who starts to play football I think it is a dream to play for a club like Barcelona, so for every player and especially for me it's a big dream come true."
Boateng only arrived at Sassuolo from Eintracht Frankfurt in July last year, making 15 appearances for the club.