c. 1400, reportour, "one who gives an account" of what was said or done by another (common 16c.-17c. in this general sense; often pejorative, "a tale-bearer"), agent noun from report (v.), or from Old French reporteur (Modern French rapporteur).
From 1610s as "one who takes down reports of law cases." In the journalistic sense, "member of the staff of a newspaper whose work is to collect information and submit it to the editors in the form they prescribe," from 1798 (from 1797 as the name of a newspaper). French reporter in this sense is a 19c. borrowing from English.