Harrison, 23, was arrested on a felony drug charge and cited for several traffic violations, including speeding, driving on a suspended drivers license and not wearing a seat belt.
He also had a misdemeanor warrant for failure to appear relating to another incident.
"Marcus Harrison has been suspended indefinitely from our football team for a violation of team rules," Arkansas coach Houston Nutt said Saturday in a statement released through the university.
"He will not play in the season opener against Troy and could face further disciplinary measures within the program after the facts are reviewed."
Harrison was pulled over just after 11 p.m. Friday for speeding on West Stone Street, according to a Fayetteville police report.
The officer reported that he asked Harrison to roll down his window, and when the senior did, there was "a very strong odor of marijuana coming from the vehicle."
The officer asked Harrison for his consent to be searched, according to the report. Harrison agreed, but before the search began, the officer asked if the player had anything illegal on him.
Harrison said he had "just a pill," according to the report. A small plastic bag containing a blue Ecstasy pill was found in the right cargo pocket of Harrison's shorts.
The officer also reported that he found two cigars under the driver's seat, including one which was still warm. Both cigars tested positive for marijuana and had a combined weight of approximately two grams.
Harrison, 23, was arrested and booked at the Washington County Sheriff's Office at 3:19 a.m. Saturday. He was released at 2:53 p.m. after posting $5,290 in bail.
Harrison has a court date scheduled for Sept. 28 relating to the charge of possession of a controlled substance. He also has an Oct. 8 court date set for the speeding charge.
"I am deeply disappointed that any student-athlete would put himself and his team in the position of losing a senior starter due to off-the-field conduct," Nutt said in the statement. "We will await the legal process and review his status in the coming weeks."
Nutt could not be reached for further comment.
Harrison's arrest came only hours after Arkansas released its depth chart for Saturday's season opener against Troy University. The 6-foot-4, 301-pound senior was listed as the starting left defensive end.
Harrison had impressed coaches with his ability to come back from a torn anterior cruciate ligament suffered during spring practice. He also showed potential after being moved from defensive tackle to defensive end.
Senior Chris Wade is listed as Harrison's backup, but it remains uncertain if he will take over the starting job or whether junior Antwain Robinson might get the nod.
Robinson was the last Arkansas player arrested. He was charged with misdemeanor shoplifting on March 18 after he tried to steal a pair of shirts from the Dillard's department store at the Northwest Arkansas Mall.
Harrison Suspended Indefinitely
Hawgs Daily Top Stories
Snapshot: Arkansas 9, Missouri 8Arkansas appeared on their way to an easy win on Sunday, but then had to hang on to take a 9-8 victory over Missouri.
Hawgs Daily3:28 PM
Spring Countdown: LBsWith the Razorbacks closing in on spring football, HawgsDaily is breaking down who we believe Arkansas' starters are at all 22 positions. We'll reveal a portion of the starting…
Hawgs Daily7:42 AM
Missouri 7, Arkansas 2Arkansas failed to clinch its series against Missouri on Saturday, setting up a rubber game Sunday.
Hawgs Daily7:37 AM
9 Hogs change uniform numbersSeveral Arkansas players will have new uniform numbers this spring.
Hawgs DailyYesterday at 8:17 AM