The I BELIEVE IN YOU hitmaker, 37, was diagnosed with the disease in May last year (05), and immediately underwent surgery to remove a lump before beginning an intensive chemotherapy course.
Dannii revealed her elder sibling's good news on her website.
She writes: "My best news to start the new year is that my sister has had her 'full remission'.
"Last year was a difficult year for many people - I'm just happy we have a close family and could all support each other."
The news means Kylie's body is free of cancer cells - but doctor's can't guarantee she is completely cured until she has been in remission for five years.