Justin Bieber's giving fans an inside look at his relationship with his son, Jack ... sharing snaps from a FaceTime call with his boy, and a photo of the two cuddling up on a relaxed afternoon.

The singer-songwriter shared a series of photos to his Instagram Sunday morning ... capturing some scenes from his daily routine -- including paparazzi photos of him drinking coffee and a screengrab of him on IG live.

On top of those, Bieber shared some pics from his time with his son ... including a photo from a FaceTime call the two had together -- presumably when Biebs was out of town and couldn't visit his baby, baby, baby.

JB's keeping little Jack's face out of these pics ... focusing on the top of his head in the FaceTime call -- so, fans are getting a chance to see Baby Bieber's face.

In another photo, Bieber's holding his son while lying back on the sun-soaked ground. His little dude's face is covered with an emoji -- but, we're sure the two look happy to be chest to chest.

As you know ... Hailey Bieber gave birth to Jack in August -- a few months after the couple announced they were expecting their first child.

Justin hasn't talked much about him publicly ... but, sources have told us he's a doting dad who's fully committed to fatherhood -- even though many online are starting rumors about his alleged drug use.