Huddersfield completed the double over former coach Nathan Brown's St Helens - a first double over these opponents since 1951 - to stay on the heels of Super League leaders Wigan.
Centre Joe Wardle scored two tries on his return from a two-match ban as Huddersfield cruised into a 25-6 lead before blotting their copybook with late defensive lapses which enabled Saints to secure a flattering, if respectable, scoreline.
St Helens, who have never finished below fifth in Super League, demonstrated considerable improvement on their 40-4 opening-day defeat by Huddersfield but one win in eight games leaves them outside the top eight and in serious danger of missing out on the play-offs.
Saints had England hooker James Roby back after almost three months out with an injured foot and gave a debut to Warrington half-back Gareth O'Brien, who got to play for his fourth club this season following previous loan spells with Swinton and Castleford.
But it was the Brough show from the moment he hoisted a high kick that forced a rare handling error from full-back Paul Wellens, and, from that position, the Giants skipper produced a cut-out pass for left winger Aaron Murphy to go over for the game's first try on eight minutes.
Five minutes later, another shrewd Brough kick caused panic in the Saints defence and, after Ade Gardner palmed the ball back towards team-mate Jordan Turner, Wardle got his hand to the ball for a crucial score awarded by video referee Ian Smith.
Trailing 10-0, Brown's response was to send on Roby but Huddersfield were set to score again when England prop Eorl Crabtree powered his way to the line only to have the ball stolen by Wellens in a two-man tackle.
Brough kicked the resulting penalty and then broke clean through the first line of defence to get back-row forward Dale Ferguson over for a try that Scotland fans will be hoping to witness in the World Cup.
Saints were struggling to find a way through their hosts' defence when Jon Wilkin, restored to the pack after three months as a makeshift half-back, took O'Brien's pass from dummy half to force his way over for a try and O'Brien added the conversion to make it 18-6.
It was a mere blemish by the Giants, however, and they thought they had scored again two minutes before half-time when Gardner lost the ball in Anthony Mullally's crunching tackle after appearing to lose his footing on the newly-laid turf and quick-thinking by Brough got Murphy over at the corner.
However, Smith disallowed the try, ruling that Mullally's tackle was illegal and match referee Richard Silverwood put the Huddersfield prop on report.
The match was held up for 10 minutes as medical staff gave Gardner oxygen on the pitch before he was carried off on a stretcher, although he was later reported to be sitting up in the dressing room.
Brough slotted over a drop goal four minutes into the second half to put his side three scores in front and clinched the victory on 52 minutes when his perfectly-timed pass got Wardle over for his second try.
Brough's fourth goal stretched his side's lead to 19 points but the Giants became sloppy in the final quarter and conceded two tries in a four-minute spell.
Centre Josh Jones went over wide out and stand-off Jordan Turner jinked his way through the middle, with O'Brien kicking his second goal.