Simple assault convictions in Washington, D.C., are punishable by a maximum of 180 days in jail. Jackson's sentencing is scheduled for April 6.
Jackson, who just finished his second season with the Colts, was arrested after an incident with pizza delivery driver Jose Bonilla-Fuentes because Bonilla-Fuentes was in Jackson's assigned parking spot at his home. Jackson allegedly punched Bonilla-Fuentes.
"I was surprised and disappointed by yesterday's verdict and we are planning to appeal," Jackson said Tuesday in a statement.
"I sincerely believe justice will eventually prevail. Nevertheless, I sincerely regret that this case ever happened and has gotten to this point. I will continue to live my life in a way that confirms I am a good and honorable citizen."
Jackson could also be punished with a fine or suspension under the NFL's personal conduct policy.
"We're disappointed to read reports of D'Qwell Jackson's misdemeanor verdict in Washington, D.C.," the Colts said in a statement Monday. "We've not had an opportunity to review any of the evidence or testimony from the trial and have not made any determination as to any action we might take as a result."
Bonille-Fuentes also filed a civil lawsuit against Jackson in January. An initial scheduling conference has been set for April 29.