"Cheer" star Monica Aldama's son, Austin Aldama, has pleaded guilty to possessing child pornography ... TMZ has learned.

In legal docs, obtained by TMZ ... Austin waived his right to trial and entered a guilty plea to one of the 10 counts of possession of child pornography -- a third-degree felony.

While Austin's adjudication is deferred ... he's been ordered to spend 180 days in county jail on weekends -- with one weekend served every month.

Austin will also be placed on probation for 10 years.

Per the docs, Austin will also be required to register as a sex offender ... and won't be eligible for early release from his community supervision until he's completed at least 5 years of probation.

As for his probation conditions ... he is prohibited from entering bars and clubs, must remain within certain city limits, is banned from associating with any criminals, must comply with any electronic monitoring required by probation, and is ordered to complete an approved treatment plan.

We reported earlier ... Austin was arrested in January 2024 after a Navarro County grand jury indicted him.

Prosecutors claimed at the time that they had evidence that included several video file names describing children -- under the age of 10 -- engaged in sex acts.