Head and neck cancer encompasses a diverse group of malignancies that pose significant challenges in their management due to their heterogeneity in clinical behavior and treatment response. Postoperative radiotherapy (PORT) is a critical component in the treatment regimen for head and neck cancer, aimed at reducing local recurrence and improving overall survival (OS). However, delays in the initiation of PORT can significantly compromise patient outcomes. This comprehensive review explores the factors contributing to such delays, categorizing them into patient-related, treatment-related, and systemic factors. Patient-related factors include health status, comorbidities, socioeconomic barriers, and psychological issues. Treatment-related factors involve surgical complications, complexities in treatment planning, and coordination challenges between surgical and radiation oncology teams. Systemic and institutional factors encompass hospital resources, staffing levels, administrative and insurance issues, and geographic barriers. The review also examined the impact of these delays on patient outcomes, highlighting the increased risk of recurrence and reduced survival rates. Strategies to mitigate delays are discussed, including improved preoperative and postoperative planning, enhanced multidisciplinary coordination, patient education, and systemic policy changes. Additionally, case studies and real-world examples of successful interventions are presented. Future directions for research and policy recommendations are also outlined, emphasizing the need for continued efforts to ensure timely PORT for head and neck cancer patients. This review aims to provide a comprehensive analysis that can inform clinical practice and policy, ultimately improving the standard of care and patient outcomes in head and neck cancer treatment.