The couple visited patients at the Starship Children's Hospital in Auckland during a visit to the city, where Bieber is promoting his new album.
He spent an hour with kids at the medical facility, signing albums before heading to a gig at the nearby Cloud venue.
Tamati Patuwai, a relative of a patient, tells Stuff.co.nz, "It was just amazing that a star like Justin would take the time to visit the kids who need a spark. It's similar to Michael Jackson when he came and visited the communities."
After his visit, Bieber tweeted, "Do something nice for someone else today. U know your truth... do it for the right reasons."
The Baby hitmaker helped raise $10,000 for the hospital through his Believe charity in December.
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