The reality star posted a topless shot of her straddling her other other half as he sits beneat her on the floor.
The rapper, who turned 27, has his face buried in her naked cleavage as she cradles his neck.
Smitten Kylie wished him a happy birthday alongside the steamy shot.
Moments later she followed it up with a similar picture, taken in black and white.
In the second picture the reality star is grinning into camera as Tyga nuzzles her neck.
“Irreplaceable,” she wrote.
The latest pictures came just hours after she treated her Instagram followers to photos of her flashing her double nipple piercing for the first time while donning some lacy lingerie.
The scantily-clad 19-year-old, who was only thought to have one nipple piercing, poses up a storm in the sultry black and white shots, which are thought to be part of a campaign to promote the star’s new underwear range.
The younger sister of Kim Kardashian can be seen posing up a storm in the sheer, black underwear set that does little to hide her modesty – let alone her double nipple piercing.