Cold, wet conditions stripped Friday's game of any colour with six of the seven tries scored from close range in a match dominated by the packs.
It was good enough for the Crusaders to put losses to the Highlanders and Hurricanes behind them, a rare double setback after marching through 2017 with only one loss.
The Bulls slumped to a fourth-straight defeat, paying the price for their lack of clinical finishing, having edged the hosts in territory and possession.
The Crusaders led by a flattering 21-7 scoreline at halftime.
They never looked like losing from there, with centre Jack Goodhue putting them further ahead with his second try soon after the break.
Reserve flanker Marco van Staden crossed late for the visitors, who had scored earlier through impressive winger Travis Ismaiel.
Winger George Bridge bagged the game's most-interesting try, from a cross-kick in the dying minutes, while their first-half scorers were Scott Barrett, Codie Taylor and Goodhue.
Rising star Goodhue also bagged a double in last year's contrasting 62-24 defeat of the Bulls in Pretoria.
The Crusaders struggled for rhythm because of the conditions and 12 penalties conceded.
One of them resulted in a yellow card for prop Tim Perry for a high tackle in the 25th minute.
They did enough, however, to make it 11 home wins on the trot over the Bulls, by an average margin of about 20 points.
There will be concern over All Blacks inside centre Ryan Crotty leaving the match late, having suffered another head knock, a problem that has plagued him recently.
The Crusaders next week face the Lions in Johannesburg in a repeat of last year's final.
The John Mitchell-coached Bulls return to South Africa, having fallen short on their three-match Australasian tour.