The 26-year-old joined United from Porto in 2007 and won the Champions League in his first season, scoring in the penalty shootout victory over Chelsea in the final in Moscow.
But the former Gremio player has barely featured in recent years and made only two appearances for United this season, prompting him to sign for Internacional on a four-year contract.
"Anderson has agreed a return to his native Brazil with Internacional on a free transfer," United announced on their website.
"Everybody at United would like to wish Anderson the best of luck for the future."
Former United manager Alex Ferguson paid around £26 million ($39.5 million, 34.3 million euros) for Anderson in 2007, but despite early signs of promise, injuries and weight problems prevented the dreadlocked central midfielder from making a lasting impact.
He spent part of last season on loan at Italian side Fiorentina and United's attempts to find a new club for him during the close-season transfer window proved unsuccessful.
In total, Anderson won nine trophies during his time at United, including four Premier League titles, one Champions League, one League Cup and one FIFA Club World Cup.
Anderson joins Darren Fletcher and Wilfried Zaha in leaving United during the January transfer window.
Long-serving Scottish midfielder Fletcher joined West Bromwich Albion on a free transfer on Monday and Zaha made his loan move to former club Crystal Palace permanent.
Source : AFP
Source: AFP