Montpellier beat Lyon 40-14 in the French Rugby Union Top 14 semi-finals on Friday, scoring four tries on the way in front of almost 60,000 fans.
They will now face either Racing 92 or surprise package Castres, who play Saturday, in the final on June 2.
Montpellier's giant Fijian winger Nemani Nadolo got the first try while Alexandre Dumoulin also scored as the visitors dominated to go in 23-9 at the break.
Louis Picamoles and Paul Willemse both scored after the break for Montpellier, coached by Kiwi Vern Cotter.
Mike Harris got a late consolation try two minutes from the whistle for Lyon, known as the perennial "yo-yo team" of the Top 14, having been either relegated or promoted four times in six seasons but who have had a great year by their standards.
Montpellier and Racing finished first and second in the regular season.