This case report describes a dog envenomed by a red-bellied black snake (RBBS; Pseudechis porphriacus) that experienced severe and life-threatening haemolysis. The dog presented with hypersalivation, facial swelling, mildly prolonged activated clotting time and the absence of neurological deficits. Envenomation was confirmed by positive identification of the snake and retrospective measurement of RBBS specific venom antigen (24 ng/mL) in serum. The dog was initially hospitalised, treated with intravenous fluids and one vial of tiger-brown snake antivenom which is recommended for RBBS envenomation in Australia. However, after 3.5 d the dog's PCV had declined to 15% and the dog was dull and tachycardic. A second vial of tiger-brown antivenom followed by a packed red blood cell transfusion was administered. A rapid clinical improvement within 12 h was observed. No free RBBS venom was detected in serum at any time point after the first vial of antivenom. Longitudinal haematology and biochemical profiling was performed to 62 d post-envenomation and revealed a gradual recovery in the haematocrit to normal reference range. Spherocyte numbers on blood smear were highest at 5 d post-envenomation and gradually declined to undetectable after 62 d. This case highlights the potential for unpredictable, severe and life-threatening anaemia resulting from RBBS envenomation in dogs.