Sardar Azmoun scored in the second half to knock Qatar out of the tournament with a game to spare.
Carlos Queiroz's Team Melli are now into the quarter-finals for the sixth time in a row.
The first-half started off at a frantic pace, but it was Iran who looked more dangerous as the half progressed.
In the 23rd minute Karim Boudiaf came to Qatar's rescue with great defending when Masoud Shojaei looked to get on the end of Ashkan Dejagah's cross.
Iran’s Morteza Pouraliganji had a header cleared off the goalline by Ahmed El Sayed and Dejagah’s right-footed strike that went narrowly wide as Iran ended the half looking the superior side.
In the 52nd minute Iran took the lead through Azmoun when he received a pass from Dejagah with his back to goal, spun Almahdi Ali with a sharp turn to apply a right-footed finish, scoring a fantastic, quality goal.
Azmoun's then went off 10-muntes later with an injury.
Mohammed Muntari had half a chance to grab the equaliser but Ali Reza Haghighi made a comfortable save from the header.
Qatar kept pushing forward but were unable to grab the equaliser.