Robbie Findley scored the only goal of Sunday's second leg in Portland to hand Real a 1-0 win, wrapping up the Utah-based club's 5-2 aggregate victory.
The 28-year-old striker poked the ball into the net in the 29th minute after Timbers goalkeeper Donovan Ricketts had failed to hold Luis Gil's shot and although Portland generally had more of the ball, they were unable to get back into the contest in front of their home fans.
Timbers defender Mamadou Danso hit the back of the net twice in the first half but both times the referee denied the hosts a goal.
In the 15th minute, the towering Gambian headed past Real goalkeeper Nick Rimando from close range but the goal was disallowed as Rodney Wallace, who had centred the ball to Danso, fouled Lovel Palmer in the lead-up.
Just after the half-hour mark, Danso was offside when he slammed the ball into the net after Rimando had saved Diego Valeri's shot.
The win at Portland's JELD-WEN Field saw Salt Lake crowned Western Conference champions for the first time, while the Timbers' maiden MLS play-offs appearance ended just short of the league-deciding match.
The home side's chances of overhauling Real were significantly hurt in the first half as first Frederic Piquionne and then Wallace were substituted due to injury but despite those setbacks, Portland dominated the second half but did not test Rimando enough.
Caleb Porter's Timbers went closest to equalising in the 57th minute when Darlington Nagbe found Valeri with a nice pass but the Argentine midfielder blasted his shot wide when clear through on goal.
Real will now travel to Kansas on December 7 for the MLS Cup to take on Sporting.
