The veteran LA Galaxy forward, on whom his country so often rely, struck the second and third goals for Jurgen Klinsmann's team after Eddie Johnson opened the scoring.
Johnson provided an early breakthrough in the 11th minute when Donovan smartly forwarded a pass from Clarence Goodson into the striker's path. Still 35 yards out from goal when he collected the ball, Johnson surged forward and in behind the Honduras defence before clipping a firm shot high and beyond the reach of goalkeeper Donis Escober.
The US were two goals in front and firmly in charge by the 27th minute, when Donovan hit his first of the contest.
This time a headed flick to Nick Rimando's goal kick by Eddie Johnson found Alejandro Bedoya on the right of the penalty area. Bedoya staved off the close attentions of two defenders to flick a pass inside, onto the chest of Donovan, and he made poking home right-footed from 10 yards look easy.
There was a momentary scare for the home team when shabby defending allowed Nery Medina to power home a header from Marvin Chavez's free-kick in the 52nd minute.
But Donovan immediately restored the two-goal cushion when Goodson's long pass over the top allowed Bedoya to dash beyond the defence and drill a low cross from the right that was converted on the run from just inside the six-yard box.
Donovan was substituted in the 72nd minute, to a warm reception, while head coach Klinsmann was dismissed from the technical area late on for apparently saying too much to referee Walter Quesada after some heavy Honduran challenges.
Mexico were victims of an upset in the second semi-final as Panama won 2-1 to set up a clash in Chicago with the United States for the title.
Blas Perez put Panama into a 13th-minute lead by blasting a fierce shot inside the near post from 10 yards out and to the right of goal.
Luis Montes headed Mexico level in the 26th minute, converting a cross from the left delivered by Marco de la Mora.
But Roman Torres had the decisive say on the hour mark, charging in to nod in a corner curled over from the left by Gabriel Torres.