Rihanna and A$AP Rocky celebrated their son RZA’s 4th birthday with a blowout bash in New York City.

The proud parents threw the fun fête at The Sloomoo Institute in Soho, Page Six confirmed.

A source told us that the “Diamonds” singer and rapper “rented out the entirety” of the popular slime museum for the evening.

Rihanna and A$AP Rocky threw RZA a 4th birthday party at the Sloomoo Institute in Soho Wednesday night (seen above). Jairo / BACKGRID

Rihanna was seen entering the downtown venue with one of her sons (seen above). ASPN / BACKGRID

We’re also told that the party was “filled with their family and friends”— including their two other kids Riot, 2, and 8-month-old Rocki — but there were no additional A-listers in attendance.

The event “included over the top balloon decorations,” the source said, noting that the kids in attendance were “playing at the different slime attractions, including Sloomoo Falls, the DIY Slime bar, and Groov’s Groovy Grove.”

The insider shared that the family had the…