Sean Cronin scored a try in each half as Leinster secured top spot in Pool 1 and a home Champions Cup quarter-final tie with Ulster thanks to Sunday's 37-19 win at Wasps.
The holders knew defeat at the Ricoh Arena would open the door for Toulouse to snatch first place in the group and a more favourable last-eight meeting.
But those fears were essentially calmed by half-time as Leinster took a 20-0 lead into the interval thanks to tries from Garry Ringrose, who powered across the line underneath the posts, and hooker Cronin, who benefitted from his pack's stellar work at a rolling maul.
Nathan Hughes, whom it was announced earlier this week would leave Wasps for Bristol Bears at the end of the season, got the hosts on the board in the second period but another driving maul saw Cronin double his tally.
Dan Robson pulled Wasps back to within two scores shortly after the hour but Leinster showed their class and a fine move through the hands released Noel Reid to secure the bonus point - Marcus Watson's late score for the home side proving immaterial.
Victory sees Leinster qualify as the third seed while Toulouse, who won 20-17 at home to Bath, advance as the seventh-ranked side and face a trip to Top 14 rivals Racing 92.
Toulouse were in command at the break, leading 17-3 courtesy of scores from Joe Tekori and Antoine Dupont.
Although Bath hit back in the second period through Semesa Rokoduguni and Zach Mercer, Toulouse held on and can look forward to a last-eight trip to last year's losing finalists in late March.
Champions Cup quarter-finals:
Saracens v Glasgow Warriors
Edinburgh v Munster
Leinster v Ulster
Racing 92 v Toulouse