Fans will know Joel from his coaching role on Australian reality show The Voice, and his regular appearance in gossip mags mags thanks to a high-profile relationship with celebrity socialite Nicole Richie.
Benji has been making news of his own lately, thanks to a rumoured romance with Cameron Diaz.
But it's in Good Charlotte that the pair made their name, with five albums released throughout the 2000s, racking up more than 10 million sales.
Benji says the idea behind their joint outing was to branch out from the pop-punk sound they'd become known for.
"The idea was to not hide behind a band name or a genre, but rather to write some songs, and find someone to record them and help us deliver the truest picture of who we are musically," he says.
They've promised to release a new Good Charlotte album in the New Year.
Other acts who announced New Zealand shows earlier this week are The Black Keys, who are returning to Vector Arena in April, and chart-topping Brit soul-pop singer Sam Smith who is on his way to Vector on April 23.
- TimeOut