Blackmon, who was selected fifth overall by Jacksonville in the 2012 NFL Draft, had a standout three-year career in Stillwater, ranking second in school history in catches (253), receiving yards (3,564) and receiving touchdowns (40). He won back-to-back Biletnikoff Awards in 2010 and 2011.
Blackmon led all NFL rookies with 865 receiving yards last season.
“I will have a productive training camp and pre-season with my team, and during the suspension I will work hard to stay in top football shape and be ready to help the Jaguars when I return,” Blackmon said in the release. “I have chosen to be accountable for my poor decision, and I sincerely apologize to my teammates, coaches, the front office and Jaguars fans for the impact of my mistake on the team.”