Fifth-seeded Verdasco snapped his fellow Spaniard's momentum with two breaks in the second set to even the match. Verdasco then dominated his Davis Cup teammate in the deciding frame with forehand winners.
"I had confidence after coming back into the game in the second set," said Verdasco, who lost last week's Monte Carlo Masters final to Rafael Nadal. "I'll have to recover quickly to be in good shape for tomorrow."
Verdasco needed 2 hours, 37 minutes for his victory, and Soderling finished in 76 minutes against unseeded De Bakker. Soderling becomes the first Swedish player to reach the final since Magnus Larsson in 1995. No Swede has won in Barcelona since Kent Carlsson in 1988.
Ferrer was denied a third straight trip to the Barcelona final, where he had lost to Nadal both times.
Ferrer controlled the tempo from the baseline and slapped a crosscourt forehand winner into the corner for another break and a 3-2 lead in the second set of a draining match in the sun.
"In the first set I felt a little heavy in the legs, I was moving poorly and I was late getting to a lot of balls," Verdasco said. "I got better with the game, it was a little strange."
Verdasco overcame his frustration to even it at 4-4 when Ferrer hit long and gradually the momentum shifted to the ninth-ranked Verdasco, who clinched the set on his fifth try as Ferrer hit in the net.
"I had the occasion and took advantage," said Verdasco, who will be going for his second title of the season. "Getting the two breaks in the second set, that was tough."
Verdasco stroked a forehand down the line for his fifth break of the match before holding serve for a 5-0 lead in the last set, which he clinched when Ferrer hit out.
Soderling set the tone by breaking De Bakker's opening service game. The eighth-ranked Soderling then saved two break points in the third game to lead 3-0 in the first set.
Soderling was up 4-0 in the second before his concentration started to slip and De Bakker broke back to cut the lead to 5-4. Soderling, who didn't drop a set all week, saved a break point before winning when the Dutchman hit into the net.