The whole fam came together Saturday for an Xmas Eve blowout, which took place at Kourtney's house -- where she spared no expense in decking the place out with holiday-themed decorations, treats and attractions ... tons of fun for both adults and kids.

There was an elaborate spread of good eats for everyone to nosh on, and grownup beverages aplenty for those who were thirsty ... of which there seemed to be a few.

The house itself looked like something straight out of a Christmas fairytale -- or a Winter Wonderland, more like. Tons of fir trees adorned the grounds, some of them even looked to be different colors (red) ... and they were fully decorated too with lights and such.

The hired talent was on point as well ... the KarJenners hired Sia to belt out some tunes for everyone ... and it seems North West was in the mood to croon too, which she totally did.

As for the ladies themselves ... everybody was in their best holiday attire, dressed to the nines in evening gowns that looked pretty fabulous on each and every one of them.

Kim chose a sparkly silver dress ... while Khloe and Kourtney went with red and white, respectively. Kylie had a black and white ensemble on, and Kendall rocked a Jessica Rabbit look -- pulling it off well, we might add.

Unclear how many people attended this thing, but by the looks of all their videos ... it appeared packed (and poppin'). You can see all of the sisters enjoying themselves with a drink or two in their hands -- ditto for all the little ones, who were having a ball.

The Kardashians have thrown some awesome shindigs in their day -- but this one might take the cake in what was clearly an eventful year for them. That's another one in the books ... and another 365 days over with for the krew.

Can't wait to see what 2023 brings ... probably a lot, we're sure.