The commission headed by Allahabad High Court (retd) Judge Vishnu Sahay was set up by the Akhilesh Yadav government in September last year.
It was given a month's time to submit its findings, including probing the role of the district administration and police, during the rioting that left 63 dead and thousands homeless.
The commission began work Oct 11, and examined more than 100 eye- witnesses. More than 700 affidavits were submitted before it.
But as its term was about to end, the commission Nov 1 sought an extension of six months, which was agreed to.
The extended term of the Sahay Commission ended May 9 and another request was made to extend its tenure by another six months. But no decision was taken as the chief minister was busy with the Lok Sabha elections.
In a decision Wednesday, an extension of six months has now been granted to the commission, an official told IANS.
The communal riots in Muzaffarnagar, a town in western Uttar Pradesh known for its sugar produce, drew national attention with most political parties slamming the state government for its inept handling of the situation.