Blackmon hauled down 64 passes for 865 yards with five touchdowns last year in his rookie season.
With the suspension, he'll be eligible to return to the active roster after the Jaguars' Sept. 29 contest against Indianapolis.
"I've made a mistake and I have no excuse," the 22-year-old said in a released statement. "I am truly sorry and disappointed in myself for putting the Jaguars in this situation, and I look forward to putting this behind me and maturing and growing as a person."
Blackmon promised to "have a productive training camp and preseason 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."