Abstract: This research explores the role of cost management in project success, aiming to: 1) identify best practices in cost management, 2) evaluate the impact of cost management on project outcomes, and 3) recommend strategies for effective cost management. A survey design was chosen to collect data from project managers and financial analysts. Using Taro Yamane's formula, a sample size of 350 respondents was determined, ensuring a 95% confidence level and a 5% margin of error. The study was conducted in the manufacturing sector in Port Harcourt, where cost management is critical. The reliability coefficient score of the survey instrument was 0.89, indicating high reliability. Findings revealed that effective cost management, including accurate budgeting, cost control, and financial reporting, significantly enhances project success. Recommendations include adopting cost management tools, providing training on cost management practices, and ensuring regular financial monitoring and reporting throughout the project lifecycle.