Almoez Ali fired Qatar into the final with a late winner after an eventful game.
The forward struck the decisive goal in the 82nd minute at Al Thumama Stadium to settle a thrilling semifinal.
Ali was the leading scorer when Qatar won the Asian Cup in 2019 but has been overshadowed by strike-partner Akram Afif this time around.
Ali came up with a crucial finish to preserve his country's hopes for back-to-back titles after a game that saw both teams give up winning positions.
Sardar Azmoun fired Iran into the lead with an overhead kick in the fourth minute. Qatar responded with a deflected equalizer from Jassem Gaber in the 17th and Afif scored his fifth goal of the tournament with a brilliant individual effort in the 43rd — cutting into the box and lashing a shot beyond Iran goalkeeper Alireza Beiranvand.
Iran leveled the game again six minutes into the second half from the penalty spot as Alireza Jahanbakhsh converted after a handball from Ahmed Fathy.
But Ali, who scored nine goals in the 2019 tournament, grabbed his second of this campaign when he fired low from inside the box late on.
Iran were reduced to 10 men when Shoja Khalilzadeh was sent off for a foul on Afif, but Jahanbakhsh still came close to forcing extra time by hitting the post in the 14th minute of stoppage time.
Additional reporting from AP