The 32-year-old American model and her ex spent the special day together with their son Sebastian, reported Daily Mirror.
The buxom star and the 28-year-old rapper married in the summer of 2013 before she filed for divorce in September 2015.
The snap sees a casual-looking Khalifa planting a kiss on Sebastian, who turns two in February.
"Bash and his daddy," Rose wrote alongside the sweet shot. Earlier in the day the US star shared a picture of the gift she bought for her son.