The university requested Blount's reinstatement, which was approved by Pacific-10 Conference Commissioner Larry Scott on Monday.
Blount will be able to play for the Ducks (No. 13 BCS, No. 14 AP) on Saturday night when they host Arizona State. He missed eight games.
Blount issued a statement saying he was grateful to Oregon coach Chip Kelly for giving him a second chance.
"Now it is up to me to prove to people that their lasting impressions of me are not what they saw in Boise," he said.
Blount punched Byron Hout following the nationally televised opener, bringing the Broncos' defensive end to his knees. The next day he was suspended for the season by Kelly, but he was allowed to keep his scholarship and practice with the team.
"We have tremendous respect for Oregon. Those coaches, we know most of those guys very well. And so, whatever they decide we're 100 percent behind. I think that's good for all involved if that's what they chose to do," Boise State coach Chris Petersen said.
Kelly later said that if Blount met certain academic and behavioral conditions, he would be allowed to return. The earliest possible date for his reinstatement was last Saturday's game against Stanford, but the Ducks waited until this week to bring him back. Kelly insisted there was no delay in Blount's return.
Kelly would not discuss the special requirements for reinstatement, calling it a private issue.
Kelly recommended Blount's return to athletic director Mike Bellotti on Sunday night. It was approved by university President Richard Lariviere before being turned over to the conference for approval.
"After a thorough review of the situation, I am convinced LeGarrette Blount paid a significant and appropriate price for the mistakes he made on the field, and that he has learned important life-long lessons," Scott said.
Blount and Kelly addressed the team on Monday morning.
"He just apologized to them again for the incident, and told them he was anxious to rejoin the team," Kelly said. Blount practiced with the team afterward.
Blount said in his statement released by the university that he would not speak to reporters.
"Until that time, I feel my actions can speak louder than anything I could say. I just want to help my teammates who have been supportive of me," his statement said.
Blount rushed for 1,002 yards last season. Redshirt freshman LaMichael James emerged as Oregon's starter in his absence.
James has run for 1,043 yards so far this season, becoming the first Oregon freshman to go over 1,000 yards rushing. He has rushed for eight touchdowns.
Oregon (7-2, 5-1 Pac-10) is coming off a 51-42 loss at Stanford this past Saturday. After Arizona State, the Ducks play at Arizona and return home to face Oregon State in the annual Civil War rivalry game.
Kelly said James will remain his starter against the Sun Devils. Blount's participation will depend on how he does in practice this week and whether there are any injuries, the coach added.
Kelly also said he was unconcerned about reaction to Blount's reinstatement.
"If I based this program on what public opinion is, I'd have a lot of problems," he said.