Austin struck five minutes before half-time, finding the corner of the net with a glorious 30-yard shot - his eighth goal of the season.
It was enough to secure another win for the hosts, who were denied a second when substitute Shaun Wright-Phillips hit the woodwork in the final seconds.
Defeat leaves Charlton just one place above the relegation zone while QPR, beaten only once in the Championship so far this season, remain in third spot - level on points with leaders Burnley and second-placed Leicester.
Rangers boss Harry Redknapp, celebrating 30 years in management - the club produced a special-edition matchday programme to mark the occasion - saw his team struggle to create clear-cut chances before Austin emphatically broke the deadlock.
They had plenty of possession early on, with Niko Kranjcar firing over the Charlton bar before Addicks keeper Ben Hamer saved low shots from Austin and Gary O'Neil.
Hamer also dived to his right to keep out Matt Phillips' 20-yard effort just after the half-hour mark.
The visitors rarely threatened, although highly-rated midfielder Jordan Cousins tested Hoops keeper Rob Green with a long-range effort shortly before Austin's goal sent the home side in ahead at the break.
With his team looking unlikely to find an equaliser, Charlton boss Chris Powell made a double substitution 13 minutes into the second half, sending Yann Kermorgant and Callum Harriott on in place of Simon Church and Bradley Pritchard.
But Rangers continued to dominate and the impressive Hamer tipped away a free-kick from Joey Barton before seeing O'Neil's deflected shot bounce harmlessly wide.
Hamer was also down quickly to stop Wright-Phillips' attempt from just outside the penalty area as Powell's men were forced to defend in numbers.
Austin fluffed a late chance to score a second, miscuing from 15 yards out following good work by substitute Andy Johnson.
Johnnie Jackson's wayward free-kick two minutes from time summed up a frustrating afternoon for Charlton.
QPR would have doubled their lead in injury time had O'Neil not missed a decent opportunity before Wright-Phillips came within inches of scoring a fine goal.
O'Neil had time and space but hurriedly fired over after being found by Johnson's left-wing cross.
And Wright-Phillips created room for himself on the edge of the box before trying his luck with a curling shot which beat Hamer but came back off the crossbar.