Runner-up last year, he will face Julien Benneteau, conqueror of champion Roger Federer, in Sunday's final after the Frenchman eliminated compatriot Gilles Simon 6-4 7-6.
Del Potro has been in devastating form and reached the title match without dropping his serve all week.
From the moment the lanky Argentine broke his Bulgarian opponent's service in the third game, when Dimitrov missed an easy volley, there seemed to be only one winner.
"My serve is really going well and that gives a lot of confidence for the rest of my game plan," Del Potro told reporters.
"I'm satisfied with this win against a player with a great potential who can be top 10 of 20 in the near future."
Despite his favourite status in the final, 2009 U.S. Open champion Del Potro did not want to talk up his chances.
"It was a bit of surprise that Roger went out but it doesn't please me as I don't pay any attention to the other half of the draw before the final," he said.
"It doesn't matter who I play tomorrow, I just have to stick with my game plan and play it hard."
Benneteau has yet to lift a tour title in his 13-year career despite reaching seven previous finals.
He retained his form from Friday when he ousted top seed Federer, although the 31-year-old had to wait for his chances against Simon.
"I handled yesterday's win ok. I put it behind me after I woke up this morning," Benneteau said.
"Though it is tough to come back on court after such a big win especially when you face someone you know so well, like Gilles."
Benneteau got his first break chances in the ninth game of the first set he and converted the third when Simon volleyed into the net.
Simon underwent treatment to his left thigh in the second set before his defensive game plan proved to be no answer to the variation of Benneteau who rushed to a 7-1 tie break win to reach the final.
"My experience is helping me and also will play a role to put the seven lost finals behind me," he added.