The Dudley-based dancer announced two weeks ago that she was battling breast cancer, but told fans she was determined to get back on the dance floor as soon as possible.
On Wednesday, the 32-year-old, who runs a dance school in the Black Country, shared a snap as she begins her treatment.
Pictured smiling from her hospital bed, and giving two thumbs up to the camera, she said she was "more determined than ever".
She wrote: "Step one to beating cancer! Rrrrrrready for this fight and more determined than ever to get back on the dance floor".
Amy, who joined the BBC dance competition show in 2017, had said that she found a lump in her breast in April, the day before going on her honeymoon with fellow dancer Ben Jones.
Her post has been flooded with well-wishes from fans and friends.
Former Strictly contestant and It Takes Two presenter, Zoe Ball wrote: "Huge love and strength to you beautiful Amy."
McFly star Tom Fletcher, who was partnered with Amy during the show in 2021 wrote: "Sending you all the love today. Us Fletchers are right behind you."
While fellow Strictly dancer Nikita Kuzmin wrote: "Love you! You got this beautiful."