But on this performance, Plymouth will themselves be in the relegation battle as pressure mounts on manager Paul Sturrock.
His side have not won a game since Boxing Day and have failed to get a winning result on their travels since November.
Charlton still have a mountain to climb but this was a comfortable and rare victory against a poor Argyle team.
It would have been even more emphatic but for some fine saves from Argyle keeper Romain Larrieu and some glaring misses by the home side, including a squandered penalty.
Plymouth had an early chance when Paul Gallagher's shot was turned away for a corner by Charlton goalkeeper Rob Elliot, but the home side took the lead on 33 minutes with a quality goal.
A short corner by Tom Soares found Matthew Spring who crossed the ball to the French midfielder Therry Racon and he fired in a beautiful curling left-foot shot from 20 yards.
Argyle went close to equalising on 35 minutes when Gallagher's free-kick hit the crossbar, but that was almost the last attempt the visitors had on goal.
Charlton dominated the second half and should have increased their lead when they were awarded a penalty after Luke Summerfield handled in the area, but Larrieu dived to his left to save Nicky Bailey's spot-kick.
The keeper then did well to keep out efforts from Chris Dickson and Tresor Kandol before Charlton got that second and crucial goal.
This time Bailey made no mistake as he got behind the Plymouth defence to fire into an empty net after Kandol's lob forward had found him in space.