"My attractive wife and...." the 42-year-old wrote on Instagram along with a picture of his 30-year-old wife sporting a baby bump.
The elder Bieber and Rebelo were married Tuesday in Montego Bay, Jamaica, a ceremony attended by the "Sorry" singer and girlfriend Selena Gomez.
"Selena and Justin flew overnight from Dallas to Jamaica for Jeremy Bieber's wedding on Monday", a source said.
TMZ reports that the brunette is 16-20 weeks along and is carrying a little baby girl.
Wrapping his arms around Selena's neck and shoulders, Justin kissed the side of her head as she circled her arms around his waist.
Justin was Jeremy's only child from his first marriage to the singer's mother, Pattie Mallette.
Jer is already the father to three kids - The Biebs, 23, with Pattie Mallette, and Jaxon, 8, and Jazmyn, 9, with Erin Wagner.
The famously on/off couple got back together - somewhat unexpectedly, this time - in October a year ago following Selena's split from singer The Weeknd.
The pair's trip comes after they enjoyed a pre-Valentine's Day getaway to Laguna Beach earlier this month, where they allegedly stayed at the luxurious Montage Hotel.
"They're just not quite there yet", the source said of Bieber spending time with Gomez's loved ones.
'They took a walk on the path in front of the resort that overlooks the ocean.
She wrote: "Yesterday was the most unbelievable day ever".
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