Ken Hudson Campbell -- who played Santa in "Home Alone" -- is hoping for a Christmas miracle ... after kickstarting a GoFundMe for help after his recent cancer diagnosis.

Campbell -- who's also appeared in other beloved classics such as "Groundhog Day" and "Armageddon" during his 35-year career span -- was diagnosed in late Oct after a tumor "elusively grew on the bottom of his mouth and began encroaching on his teeth."

The statement on the GoFundMe says he's scheduled for a 10-hour surgery to remove the tumor Thursday ... which will also remove a large part of his jawbone.

Additionally, he'll undergo reconstructive surgery and rounds of radiation and chemo ... with a lengthy 6-month recovery period.

Unfortunately, Ken lost his SAG-AFTRA health insurance in Jan 2022 following the pandemic ... and even though he's found new insurance, substantial out-of-pocket costs are still anticipated -- hence the GFM.

At the time of writing, it has reached a little over $58K of its $100K goal.

The statement emphasizes the surgery could affect his future employability ... adding: "We're asking for your help so that Kenny can use the time ahead to return to health, and spend more time with family & friends."