A seven-foot, 225-pound power forward and center for powerhouse Findlay Prep, he told Inside the Auburn Tigers that he chose Auburn over Georgia Tech, St. Mary's, Boston College, Washington State and others.
"I have committed to Auburn and I am really excited about," he said. "I thought Auburn is going to be the best fit for me so I decided to go ahead and sign and not wait until the spring."
Griciunas, who is from Lithuania, said, "I think Auburn is going to be a real good fit for me," he said. "They use their big men a lot and their team is getting better and better.
"With Rob Chubb being a senior this year it is a good opportunity for me," he added. "I think I can fit in there and play right away."
Playing on a team loaded with prospects, Findlay Prep is off to a 4-0 start. In his last game on Friday night he scored a team-high 17 points in a 91-53 victory.
Findlay's Nigel Williams-Doss is committed to Washington, Allerick Freeman to UCLA, Stanford Robinson to Indiana and Christian Wood to UNLV while Gavin Schilling has offers from a variety of Division I programs.
"It feels real good to make my decision," he added. "Now I can concentrate on playing for my team this season and not have to worry about my college choice."
Griciunas, whose hometown is Siulte, a city of about 30,000 in Lithuania, took an official visit to Auburn this fall and said he liked the campus as well as the city. "I really like Auburn," said the big man, who noted that he is interested in studying international law and business in college.
On Sunday the Tigers got a commitment from another seven-footer, Ronald Delph, who plays on the prep school team at IMG Academy in Bradenton, Fla.
The Tigers also are expected to sign point guard Tajh Shamsid-Deen in the early period.