Hailing the fervent fan support and quality of life in Shanghai, former Brazil international Oscar has ended his eight-year stint in China's top-flight with mixed feelings, after confirming his return to hometown club Sao Paulo.

Oscar, a former Chelsea midfielder and a member of Brazil's 2014 World Cup squad, has rejoined his boyhood club in southeastern Brazil on a free transfer, announced by Sao Paulo president Julio Casares on Tuesday, after playing eight seasons in the Chinese Super League with reigning champion Shanghai Port FC.

In an emotional post on Chinese social media, the 33-year-old playmaker appreciated the unwavering support from his fanbase in the eastern metropolis, which he has embraced as his adopted home and helped the Shanghai club win three league titles, a Chinese FA Cup and a Super Cup during his tenure.

"After eight years wearing this jersey with so much pride, it's impossible not to feel a mix of emotions as I say goodbye," Oscar wrote in English on his Weibo account on Wednesday.

"I want to thank the club for believing in me from day one. The trust, the support, and the conditions you always provided were fundamental for my growth as a player, and as a person," said Oscar, who joined Shanghai Port from Premier League giant Chelsea in a shock transfer worth a CSL record 60 million euros ($62.5 million) in 2016.

"And to the fans… How can I describe what you mean to me? You were our fuel through every moment. Playing here was a privilege, and feeling your energy in every match is something I will never forget.

"I take with me incredible memories and the certainty that I gave my all for this club. I leave with a heart full of gratitude and pride for everything we achieved together. This club will always be my home, and this fanbase, my family."

A proud product of Sao Paulo's youth program, Oscar was promoted to the club's senior side in 2008 at the age of 16, played five seasons in Brazil's domestic league before taking center stage in European soccer with Chelsea in 2012.

After spending over three years at Stamford Bridge, Oscar joined the high-profile legion of star imports flocking to the CSL, drawn by lucrative wages, midway through the 2016-17 season, when he, at the age of 25, was one of the most globally sought-after rising stars.

The likes of Oscar's fellow countryman Alexandre Pato, former Argentine international Carlos Tevez and Belgium star Axel Witsel were also among big names lured to the CSL by the then financially mighty clubs, funded by billionaire owners from China's retail and real estate sectors, during the free-spending 2010s.

Oscar, however, has proved the longest-serving and most consistent leader of them all, making 248 appearances for Shanghai Port, scoring 77 goals and providing 141 assists across all league, domestic Cup and continental competitions.

The attacking midfielder reportedly earned the world's third-highest annual salary — 24 million euros — from his Chinese club, with his earnings exempted from a CSL salary cap of 3 million euros for each import imposed by the Chinese Football Association in 2020, just a year after he signed a contract extension with Shanghai Port.

His new three-year contract with Sao Paulo, free of fees after his five-year extension with Shanghai expires at the end of this month, reportedly earns him 2.3 million euros a year.

The safe, comfortable and affluent life in China, though, made his departure a tough decision, Oscar confessed in an interview with Brazilian newspaper Folha de S Paulo in September.

"I love Shanghai, but it's just too far away from home for us. We can't stay here forever," he told the paper in Portuguese from his Shanghai apartment, overlooking the scenic Huangpu River. "My mom is getting older, my sisters are having babies. We want to be closer to home."

"Wherever I go, it won't be like here. There's no way to change that. The quality of life in China is unique. I've never seen anything like it in Europe.

"My kids go to school and come back home by bus without me worrying about their safety. We can go out as much as we want at 2 am or 3 am, and go anywhere and nothing will happen.

"There are no drugs here. It's like something from another world. Only those who are here, living here, understand how it feels," said Oscar, who wiped away tears as he waved to fans amid chants of "Oscar, stay!" following his final home game in Shanghai on Dec 3.

The Shanghai club addressed Oscar's departure in a statement released on Wednesday, paying tribute to the Brazilian star's contribution to the team on and off the pitch.

"Captain, you are always our pride," said the statement.

"Thank you for fighting so hard for the team, for the club family and for bringing so much joy and glory for our fans. This club is your home forever.

"Obrigado boa sorte (Thank you and good luck)."