Montpellier booked a Challenge Cup final against Ulster by defeating Dragons at the Septeo Stadium.
Tries from lock Tyler DuGuid and scrum-half Alexis Bernadet and eight points from Thomas Vincent's boot sealed a home win and a place in Europe's second-tier tournament finale in Bilbao on Friday, 22 May.
Dragons responded with two tries from centre Aneurin Owen in a resilient performance.
The Welsh side were defensively dogged but were starved of possession and territory and could not capitalise on limited attacking opportunities.
The Dragons' exit has ended Welsh interest in this season's European tournaments but Filo Tiatia's side can be proud after enjoying a much improved season.
It was a seventh successive win in this season's tournament for Montpellier and the French side are looking for a third Challenge Cup success.