The 27-year-old has struggled to break into the Charlton starting lineup on a regular basis and as a result has found the net just once this season.
With that in mind, Addicks manager Chris Powell has allowed the striker to head for Griffin Park to improve his match sharpness.
"Bradley is a proven goal scorer in this division and is a player we have been looking at for a long time," Brentford's sporting director Mark Warburton told the club's official website. "He is a player that was chased by teams in the Championship and some of our rivals for promotion this season, so we are delighted we could secure him.
"We are very pleased to bring him to Griffin Park and hopefully he can help us achieve our aims and ambitions for the season.
"He had an outstanding season in League One last season and hopefully he can continue that form this time around."
Wright-Phillips scored 22 times as Charlton were promoted to the Championship last year.