Background: Unilateral proptosis is a clinical sign with a wide spectrum of etiologies ranging from benign inflammatory conditions to life-threatening malignancies. A timely and accurate diagnosis is crucial for optimal patient management and outcomes. Objective: This study aims to analyze the underlying causes of unilateral proptosis in different age groups and assess the associated clinical presentation and outcomes. Methods: A prospective observational study was conducted on 29 patients presenting with unilateral proptosis. The cases were categorized based on age, etiology, and clinical course. The pediatric group (<= 15 years) and adult group (>15 years) were analyzed separately to identify distinct patterns in etiology and prognosis. Results: Proptosis was observed in all patients (100%). Associated symptoms included diplopia (31.5%), diminished vision (27.5%), eye pain (20.6%), and systemic symptoms such as headache and fever (13.7%). In the pediatric population, the most common causes included orbital cellulitis (27%), retinoblastoma (18%) and optic nerve glioma (18%). In adults, thyroid eye disease (16.6%), Pseudotumor of the orbit (11.1%), and orbital cellulitis (11.1%) were among the frequent etiologies. Malignant conditions were more prevalent in children, whereas inflammatory and vascular causes were more common in adults. Conclusion: The etiology of unilateral proptosis varies significantly with age. While infectious and malignant causes predominate in children, inflammatory and vascular pathologies are more frequent in adults. A systemic approach to evaluation, including clinical examination and imaging, is essential for accurate diagnosis and appropriate management.