Steve Pettibone was last seen at 7:30 a.m. on Monday when he left his home in Belleville to go to work at the Brockville Recorder and Times, where he is the sports editor.
His colleagues say he never arrived.
Police say Pettibone is 39 years old, about five foot 10, has brown eyes, balding hair and a goatee.
They say he was driving a grey 2013 KIA Rio (with Ontario licence plate BPMT 499) when he left home.
The newspaper's managing editor, Derek Gordanier, has written a column appealing for assistance in locating the journalist, saying the disappearance is "out of character" and has left the newsroom "incredibly concerned."