La Rochelle book Top 14 final date with Toulouse
La Rochelle, who beat Irish giants Leinster in a thrilling match last month to win their second successive European crown, now have a chance to win their first Top 14 title in Paris next Saturday.
Toulouse thrashed Racing 92 41-14 in Friday's first semi-final.
They were always in control against Bordeaux at the Anoeta Stadium in San Sebastian in the Spanish part of the Basque Country.
South African Dillyn Leyds crossed over for La Rochelle's first try after nine minutes before Pierre Bourgarit increased their advantage after 21 minutes, with both tries converted by Antoine Hastoy.
When Paul Boudehent scored the third try just before half-time, again converted by Hastoy, La Rochelle were so comfortable that even the penalty try they conceded in the 49th minute did not rock them.
Two penalties from the boot of Matthieu Jalibert gave the scoreline an air of respectability for Bordeaux-Begles but La Rochelle can dream of more silverware next weekend.