Nigeria's extensive road network faces severe deterioration due to chronic under-maintenance, overloading, extreme weather, and funding constraints. Traditional Hot Mix Asphalt (HMA) rehabilitation, while widely used, is resource-intensive, costly, and environmentally burdensome. This study conducts a comprehensive comparative analysis of Cold In-place Recycling (CIR) and HMA for pavement rehabilitation in Nigeria, focusing on technical performance, lifecycle costs, and cost-benefit outcomes under local conditions. Employing a mixed-methods approach, the research integrates literature review, case studies across geo-political zones, Lifecycle Cost Analysis (LCCA), and Cost-Benefit Analysis (CBA) using metrics such as Net Present Value (NPV), Benefit-Cost Ratio (BCR), and Internal Rate of Return (IRR) over a 20-year period. Data sources include secondary reports from federal agencies, international benchmarks adjusted for Nigeria, and stakeholder insights. Findings reveal that CIR offers 20-50% initial cost savings, lower lifecycle and user costs, reduced construction disruptions, and superior environmental benefits (23% lower CO₂ emissions and significant virgin material conservation). CIR demonstrates higher NPV and BCR (1.8-3.2) compared to HMA, proving more economically viable for medium- and low-volume roads, though hybrids may suit high-traffic corridors. Challenges include limited expertise, equipment availability, and weather dependency for CIR. The study recommends greater adoption of CIR to optimize budgets, enhance sustainability, and address infrastructure deficits.