The top seed from Switzerland ended the upset run of Austrian Stefan Koubek with a 6-2, 6-1 rout, setting up a final encounter with No. 8 Jarkko Nieminen of Finland.
"I've felt my concentration and other parts of my game improve," said Federer, who improved his 2003 record to 30-6. "I've been really happy with the way it's been going. I've been raising my game all week, I'm looking forward to going for another title."
Federer, 21, has claimed two titles this season and six in his career. He beat Nieminen for the second time in as many meetings en route to his triumph at Marseille in February.
The unseeded Koubek had performed well this week after seven consecutive first-round losses.
The 26-year-old Austrian missed a month of play with a rib injury until mid-February, then couldn't get his game untracked until this week.
Nieminen will be taking his fourth shot at a title, having been beaten in clay title matches last year in Estoril and Mallorca.
He eased into the trophy contest as fifth-seeded Russian Yevgeny Kafelnikov fell victim to the neck injury which had hampered his game all week.
The 29-year-old had to quit a doubles match earlier in the week and couldn't continue Saturday, handing Nieminen a 6-4, 0-1 win as he quit after an on-court visit from ATP trainer Doug Spreen.
"This is not really the way you want to reach a final," said Nieminen, who will become the first Finn to break into the top 50 in the past three decades, moving to a likely 37th.
The 21-year-old Nieminen, who also lost a final indoors at Stockholm in 2001, is pleased with his game as the French Open draws nearer.
"It takes me couple of weeks to get going, some time to find my best form," he said. "But I trust myself more this year. I know my game better and have more experience and confidence. I'm very satisfied with the way I'm playing."