Kim Kardashian Throws Son Psalm 'Ghostbusters'-Themed Birthday Party

Halloween's still a few months away, but Kim Kardashian's already in the spooky season -- throwing her son Psalm a Ghostbusters-themed bday party!

The reality TV star and mogul posted footage from her son's fifth birthday party Saturday to her Instagram story ... and, Psalm seems ready to join the squad -- 'cause he's got his jumpsuit and proton pack ready to go.

Check out the vid ... Kim had a huge cartoon cardboard cutout of Psalm in full Ghostbusters gear ready to greet the arriving guests -- and each kid got their own little novelty pack, just like the ones in the flick, to take home with them.

And, the iconic specter Slimer appeared all over the party ... with bright green decorations and little statues of the gross ghost overlooking a table of goodies for the kids.

Even the food fit the theme ... nachos topped with green cheese and a two-tiered white and green birthday cake with the Ghostbusters logo on the front -- so, the Kardashians really committed to the aesthetic.

Kim finished off all her posts by sharing a pic of her holding Psalm and writing, "My baby is 5 😫🥺" ... a stark reminder of how old Kim's kiddos are getting. She added a long, sweet Instagram tribute to her youngest too -- shouting out the calm energy he brings to the house.

Of course, KK's a mother of four -- 10-year-old North, 8-year-old Saint -- who made a cameo at the party, trying to knock down a piñata -- 6-year-old Chicago and Psalm. She shares all of them with Kanye West.