The 23-year-old recording artist reunited with the 25-year-old singer and actress at her house Sunday in Los Angeles, TMZ reported Tuesday.
Sources said Bieber's visit wasn't romantic and that he and Gomez were joined by mutual friends. The actress' boyfriend, singer The Weeknd, was away on tour, but reportedly aware of the get-together.
Bieber, Gomez and their pals hung out until "at least midnight" before parting ways. Insiders said Bieber and Gomez reconnected after Gomez announced in September that she'd undergone a kidney transplant.
Gomez split from Bieber in 2014 after several years of on-again, off-again dating, and was first linked to The Weeknd in January. She shared lyrics to her romantic new song "Wolves" on Wednesday, which some believe is about The Weeknd.
"I've looked for love in every stranger / Took too much to ease the anger / All for you, yeah all for you / I've been running through the jungle / I've been crying with the wolves / To get to you, oh to get to you," the lyrics read.