"Awww look at my little Angela at 14!!!!!! Hahaha I LOVE YOU !!!! @blacchyna," he wrote.
Kardashian and Blac Chyna share 6-month-old daughter Dream. The reality star also posted a photo of a younger Blac Chyna.
"On my first episode of Rob's Random Cornball Thoughts is This young lady who grew up to be the woman I love and the mother of my child. She is beautiful and gave me my first child. @blacchyna," he said.
Kardashian and Blac Chyna ended their engagement in February following a highly-publicized split in December.
Sources denied in April that the pair are back together after they had a flirty night out in Los Angeles.
"They are co-parenting and independently working on themselves but they're more cordial now than they have been, which is why they hung out recently," a source told E! News. "But by no means are they back together."
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