The Spain winger made six appearances for Barca after progressing through the ranks at La Masia, but has cut his teeth in senior football with Sevilla and Everton, before spending the second half of last season on loan at AC Milan.
Deulofeu scored four goals in 18 games for the Rossoneri, form good enough to earn a recall to the Spain senior side and a return to Barca - who triggered a buy-back clause in the deal that took him to Goodison Park.
Breaking into a front three featuring Neymar, Luis Suarez and Lionel Messi is a daunting prospect for anyone, but Deulofeu is determined to break through, having dismissed suggestions that Barca could look to sell him on in this transfer window.
"I am very happy to be back at Barcelona," Deulofeu told reporters after captaining Spain Under-21s in their European Championship final defeat to Germany.
"It is my home and it was a shame I could not go back sooner.
"It is already decided. This year I will stay at Barca for sure. I am ambitious and I want to play with the best.
"I am very happy to have this opportunity that I have never had, to play in the first team of Barca."