She posted a video of her ringing a bell at the Beatson cancer centre in Glasgow to mark the occasion.
Ms McKelvie announced in February that she would be stepping aside from her role as minister for equalities and older people for a “short time” for treatment for a then undisclosed medical condition.
On Friday, she tweeted: “It’s been a long hard road but today in The Beatson @Beatson_Charity I rang the bell to recognise the end of my treatment for breast cancer.”
She thanked her sons and her partner, Justice Secretary Keith Brown, for their support during her treatment, as well as wider family and friends and “our incredible NHS Scotland”.
Ms McKelvie, who was re-elected as the MSP for Hamilton, Larkhall and Stonehouse in May, added: “From my first screening to the last treatment they have been amazing, the consultants, the amazing chemo & breast cancer care nurses, the @ScotAmbNCCC & my GP have given me exemplary care.”
She also urged other women: “Please go to your screening appointments they work! #CheckYourBoobs #ScreeningWorks.”