An Australian mother who faked her six-year-old son's cancer diagnosis to solicit donations and fund her lavish lifestyle has been sentenced to more than four years in prison.

The 45-year-old from South Australia shaved her son's head and eyebrows, bandaged his head and hands, and medicated him as part of a ruse to trick family and friends into raising thousands of dollars.

The woman - who cannot be named for legal reasons - pleaded guilty to one count of engaging in acts likely to cause harm to her son and 10 counts of deception.

At a sentencing hearing on Wednesday, a District Court judge described her actions as "cruel", "calculated" and "manipulative".

The woman's deception started after her son went to see an ophthalmologist, a specialist eye doctor, after an accident, the court heard.