The Saints owed their win to a dominant first-half performance in which they scored 28 points in the opening 29 minutes.
Agnatius Paasi opened the floodgates after Owen Dagnall's fourth-minute break from a scrum with ex-Newcastle star Jackson Hastings landing the first of five successful kicks.
The Saints built on that fast start as Lewis Murphy crossed twice in the space of eight minutes before the midway point of the first period.
Former Brisbane Bronco and St George Illawarra Dragon Tristan Sailor set up Murphy's second try and the Australian stand-off produced another superb offload to send ex-Newcastle and St George star David Klemmer over.
Jake Wingfield then set up Deon Cross and Saints were out of sight before the 30-minute mark.
The start of the second half was an arm wrestle, but Toulouse replied through tries from Benjamin Laguerre, Luke Polselli and Tyler Dupree, with Jake Shorrocks landing two goals.
But the boot of Hastings had the final word as he completed a personal 10-point haul.
Saints head coach Paul Rowley told Sky Sports: "We had some standards that we wanted to uphold and we didn't quite manage to do it.
"All credit to Toulouse for having the resurgence. Nonetheless, we would have taken that result before we got here."
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