Barnsley have earned a vital victory at The Valley thanks to a second-half strike from Tomasz Cywka.
The Polish midfielder buried the ball in the top corner from an acute angle to break the deadlock early in the second half.
A bright first 45 minutes for the visitors stamped their authority on the match, with Jacob Mellis and Craig Davies menacing throughout.
Charlton tried to rally and were denied a strong penalty appeal on the hour when Chris Dagnall tangled with Chris Solly.
The Addicks were forced to search for an equaliser with 10 men in the closing stages when Ricardo Fuller pulled up with a hamstring problem after Chris Powell had used all three substitutes.
Barnsley held on for all three points to leave the home side languishing in the relegation zone.
