The Bluesox had victory in the bag up at the break, when they led 24- 0, their Australian scrum-half, Gavin Clinch, having opened his account for the club with two tries. In the second half, Damian Gibson rounded off a superb move that spanned almost the length of the field to condemn last season's Super League runners-up to an embarrassing opening-day defeat.
Chris Ryan did manage a consolation try with a good solo effort, but in truth even that flattered a desperately disappointing London side, who looked to be suffering a hangover from last week's heavy Challenge Cup semi-final defeat by Wigan.
The Broncos had the better of the opening stages, but they could not find a way through a resolute defence and paid the price after 16 minutes, when Clinch dived over after Kelvin Skerrett had been stopped inches short of the line.
From then on it was all Halifax, as they made London pay heavily for their 21-18 Cup win last month, which had brought complaints of dangerous high tackles from the Bluesox.
Martin Moana doubled the lead after 23 minutes, bursting on to a short ball from Clinch and four minutes later Clinch took advantage of Butch Fatnowna's failure to gather a kick through for his second try of the half. Gary Mercer added a fourth try before the interval, with Martin Pearson converting all four tries.
Halifax produced a contender for try of the season on 49 minutes. Fereti Tuilagi made the vital break and received support from Gibson, who outpaced the cover to round off a wonderful move.
Pearson added a penalty to complete the scoring and despite Ryan's try and Terry Matterson's conversion, London never threatened a comeback.
Leeds overcame the loss through injury of their inspirational captain, Iestyn Harris, to open their Super League programme on a winning note at home to Warrington Wolves.
Although the Australian centre Michael Eagar scored a spectacular try early in the second half to put the Wolves back in the game, Leeds proved the more consistent force, finishing the stronger and scoring five tries against one.
Leeds put their mark on the game when they scored 12 points in three minutes early on. Stand-off Tony Kemp played a key role in both tries, putting centre Richie Blackmore over from close-up play and then sparking off some clever handling for scrum-half Ryan Sheridan to cross.
With captain Harris tacking on both conversions and also adding a 25th- minute penalty goal, Leeds went 14 points clear.
All the Wolves could produce in the opening half was a close-in penalty from Briers after Brendon Tuuta had gone close to a try.
Warrington bounced back into the game within three minutes of the restart with a spectacular try from the Australian Eagar. He raced from 80 metres out, and when defenders Paul Sterling and Harris collided in trying to bring him down, he was able to run clear to touch down. Briers goaled to make it 14-8.
Harris was injured in the clash with Sterling and was carried off, but Leeds made sure of the points when they added further tries from Sheridan and the substitute Daryl Powell.