The 6-foot-3, 310-pound Worthy was a first-team Associated Press All-American and is rated 20th overall on ESPN draft expert Mel Kiper Jr.'s Big Board.
A key cog in a Spartans defense that ranked fifth nationally in the FBS this season, Worthy finished with 30 total tackles, including 10½ for loss, 3½ sacks and two blocked kicks. He has been projected as a potential first- or second-round pick in the April draft.
Worthy was Michigan State's first All-American defensive tackle since Ronald Curl in 1971. He helped the Spartans go 11-3, winning the Big Ten Legends Division title and beating Georgia 33-30 in triple overtime at the Outback Bowl.
He also said his father suffered a stroke before the start of the 2010 season, something which impacted his decision.
"My father is slowly but surely progressing back to where he needs to be," Worthy said. "One thing that helped lead to this decision is the simple fact that he's not getting the provided care he needed to make as fast of a recovery. He's near and dear to my heart. ... (Coach Mark Dantonio) knows it's my obligation to do whatever is required for my family and that's what led to this decision as well."
Dantonio said Worthy's decision is understandable.
"When you have an opportunity like that, it's very difficult to pass up because of the financial situation you would be in at this point in time," Dantonio said. "We wish (Worthy) the best at Michigan State and we will miss him tremendously."
Dantonio said he and Worthy, who is from Huber Heights, Ohio, enlisted the opinion of NFL general managers, scouts and coaches.
"What we wanted to do is make sure the dollars are there on the front end if he decides to do this," Dantonio said. "That's the indication we received."
Brian Bennett covers Big Ten football for ESPN.com. Information from The Associated Press was included in this report.