Athletics Director Jeff Long announced the decision at an evening news conference in Fayetteville.
Long said assistant coach Taver Johnson would take over as interim coach through the completion of spring practice.
Petrino was let go for "abusing his authority" and "jeopardizing the integrity of the football program," the AD said.
Arkansas placed the 51-year-old Petrino on paid leave last week following revelations he was with a 25-year-old female athletic department employee when he crashed his motorcycle April 1 southeast of the Fayetteville.
The young woman had been hired last week.
Petrino, who is married with four children, admitted an initial statement indicating he had been alone during the crash was false.
The coach said he has "been in constant pain, medicated and the circumstances involving the wreck have come out in bits and pieces."
Petrino compiled a 34-17 record in four seasons leading the Razorbacks, including an 11-2 mark and a Cotton Bowl win over Kansas State this past season.