South Korean police reported that his manager found him unresponsive at his Seoul apartment on Wednesday night.
"He looks to have committed suicide, but an autopsy is being reviewed to determine the exact cause of death," police added.
Moonbin "unexpectedly left our world and became a star in the sky," Fantiago remarked. Before joining Astro in 2016, 18-year-old Moonbin was an actor and model.
He performed with Astro member Sanha since 2020. Moonbin & Sanha ended their globe tour in Bangkok on 8 April.
Fantiago added all Astro members would return to Korea on Thursday for Moonbin's wake. The label begged fans to "refrain from speculative and harmful reports" so Moonbin's family could mourn in peace.
Billlie member Moon Sua is Moobin's sister. The siblings had discussed their dependence in public interviews.
Moonbin is the latest K-pop singer to die: In 2019, singer-actress Goo Hara was discovered dead at her Seoul residence. K-pop sensation Sulli, her close friend,
committed suicide after a protracted battle with internet bullying the same year. Minwoo of 100% died at home in 2018 from cardiac arrest, according to his label.