<p>Zoonotic protozoan diseases continue to pose a major global health threat, particularly in the rapidly emerging One Health framework that connects the health of humans, animals, and the environment. Of these diseases, <i>Toxoplasma gondii</i>, <i>Balantidium coli</i>, and <i>Babesia</i> spp. present major challenges due to their complex life cycles, wide host range, and morbidity in both humans and animals. In this review, classical and more recent research are explored in the context of their epidemiology, potential transmission routes, pathogenesis, new diagnostics, and treatment options. A key focus of the review is <i>Toxoplasma gondii</i> due to its high global prevalence and its recent association with neuropsychiatric and chronic human diseases. <i>Balantidium coli</i> is the only ciliated protozoa known to infect humans and aside from <i>Toxoplasma</i>, may be the least reported zoonotic protozoan parasite worldwide, but nevertheless continues to exist especially in areas that are poorly sanitized and among those closely associated with pigs. <i>Babesia</i> spp. are now one of the fastest emerging zoonotic protozoan parasites, with their association with tick-borne disease and are being reported outside endemic areas due to climate change and expanding fragmentation of the geographical range of these vectors. Diagnostics and treatment options are highlighted as is the gap in vaccine development and parasite surveillance. The review concludes with the need for integrative approaches that blend veterinary, medical, and ecological expertise to address prevention and control of protozoan zoonoses in the dynamic and rapidly changing global environment.</p>