By Simon Cambers
The fifth seed's victory set up an eagerly anticipated re-match with Rafael Nadal in the final after he became last year the first player to beat the Spaniard at Roland Garros.
In sweltering conditions, Soderling looked jaded at the end when Berdych pushed a backhand into the tramlines to end a three hour 27 minute contest full of fierce baseline rallies.
"It was more than tough," the sweat-drenched 25-year-old said on court. "Tomas played really well today.
"It was really tough for me to play my game, because he was hitting the ball so hard and so flat. Everything was 10 centimeters from the baseline."
Soderling, who beat Roger Federer in the quarter-finals, could hardly believe that he was back in the final after losing to Federer last year.
"It's unbelievable. When I came here, I was thinking about only the first round, getting past the first round. Now, two weeks later, I am in the final again. It's better than the best dream ever," he said.
Soderling broke serve in the sixth game of the first set when Berdych double-faulted and went on to win the opener.
Both players struggled for control in the warm air, often firing shots over the baseline, but Berdych began to find his range to win the second and third sets.
The Czech, playing in his first grand slam semi-final, had a chance to break the Soderling serve right at the start of the fourth but the Swede pummeled down an ace.
Soderling struck in the sixth game, breaking when 15th seed Berdych netted a backhand, to set up a deciding set.
After trading early breaks in the fifth, Soderling broke twice more to reach his second grand slam final.
Berdych showed signs over the past two weeks that he is finally beginning to realize his full potential and said he would take many positives from his run.
"Every match I played here gives me a lot of confidence until the last one," Berdych, who beat British fourth seed Andy Murray in the fourth round, told reporters.
"It just shows that I can play with all those guys, you know, I can beat all of them. I'll just keep going and waiting for another chance."
(Writing by Martyn Herman, Editing by John Mehaffey)