After winning just one of their previous six, the Broncos and - in particular halves Ben Hunt and Anthony Milford - rebounded to form. Hunt crossed in the opening half for his first four-pointer since round eight.
Brisbane drew first blood when Boyd threw a looping cut-out pass to set up Lachlan Maranta before coming up with an almost identical play on the other side of the field to put Corey Oates over in the 19th minute.
Both sides failed to trouble the scoreboard for almost 40 minutes with the Broncos going close on three occasions - with Boyd held up, Oates losing the ball as he reached for the corner and Maranta putting a foot over the sideline.
However, the game was iced when James Roberts burnt three defenders to score a scintillating solo effort and Oates ran the length of the field.
South Sydney fullback Cody Walker, who during the week shunned a Brisbane offer and re-signed for three seasons with Souths, and was his side's best, scoring a late consolation try.
Luckless Broncos centre Jordan Kahu is facing yet another stint on the sidelines after aggravating a pec injury in his first game back after missing the past month.
Hooker Andrew McCullough also has a nervous wait on his hands after being put on report for a high tackle on Angus Crichton.