The signing is Chris Powell's first since becoming Charlton boss last week.
The new Addicks manager told the club website: "I am very happy to have a player of his calibre joining our squad."
Wright-Phillips, who has scored 13 goals this season, said: "I'm delighted to join Charlton.
"They're a club which I'm sure is heading in the right direction and, as soon as I spoke to the manager, I knew I wanted to be a part of it."
Wright-Phillips, who was the subject of an offer from Premier League side Blackpool early in the January window, has not featured for Plymouth since scoring in Argyle's 3-2 win at Bristol Rovers on 4 January.
Argyle have since lost four of their last five matches to slide six points adrift of the League One play-off zone.
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