Paulinho, 29, scored nine goals in 49 appearances for the Catalans after signing for 40 million euros ($47 million) last August, helping them win the La Liga and King's Cup double.
Meanwhile, NAIJ.com previously had reported that Brazil worldwide Paulinho joined Barcelona after the club activated his €40 million buyout clause.
Paulinho helped Guangzhou to two league titles during his first spell at the club.
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The former Dynamo Kiev player scored an extra-time goal and one of Croatia s penalties in a 4-3 shootout win over the World Cup hosts in Sochi on Saturday.
He has also won a Copa Libertadores and a Club World Cup with Brazilian club Corinthians.
Barcelona have announced the sale of Paulinho to Guangzhou Evergrande.
His form, coupled with the sizeable transfer fee spent just a year ago made the announcement of the 12-month loan all the more puzzling.
"I chose to return to the Super League this time, hoping to bring more championships to Guangzhou and Guangzhou fans". It is understood that Barcelona have a deal in place for the Gremio midfielder, who is a promising talent and can strengthen their creative unit. Thus, his prospects of further establishing himself as a regular first-team player at Barcelona were close to none.