The Spaniard produced another near-faultless display on his favourite stage to beat the Austrian 22nd seed 6-2, 6-3, 7-6, celebrating his victory by kicking a ball into the crowd and leaping high into the air.
A routine-looking win got a little sticky at the end as Melzer launched a late fightback but it clearly meant the world to Nadal, who now has the chance to set the record straight with Sweden's Robin Soderling in Sunday's final.
"I was nervous during all the tournament, but today I was a little bit more relaxed because I was already in the semi-final," Nadal told reporters. "I am there. I am at the last match. I am where I dreamed to be a long time ago."
Soderling's shock victory over Nadal in last year's fourth round is still the Spaniard's only defeat in 38 matches at Roland Garros which have brought him four titles.
A fifth is now looming after reaching the final without the loss of a set as he did in 2007 and 2008, although for a while near the end Melzer did threaten to blot Nadal's copybook with soem brave attacking play in a late fightback.
Serving for the match at 5-4, Nadal was broken to love and was reduced to laughter when his second serve on break point bounced before it even reached the net.
Temporarily thrown off his stride in the early evening sunshine, Nadal had to dig deep to finish off an opponent who was determined not to depart his first grand slam semi-final without putting on a show.
In the end Nadal, as he usually is on clay, was just too powerful and too accurate and he regained his rhythm to win the third set tiebreak despite squandering two match points.
"I made some mistakes and in the 5-4 game I played a terrible first point," Nadal said. "I played forehand down the line, three metres out. I was a little bit nervous after that."
Turning his thoughts to Sunday's final Nadal, yet to lose a match on clay this year including a Monte Carlo-Rome-Madrid hat-trick, remained wary.
"I'll try to play my best tennis," he said "That's what I have to do. If not it will be almost impossible to win over Robin because he's playing an amazing level."