In an era where the agility and responsiveness of Agile project management are paramount, the integration of structured models like the Capability Maturity Model Integration (CMMI) presents a blend of unique opportunities and challenges. This study conducts a comprehensive systematic literature review of 23 scientific articles, chosen through the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology, to explore the benefits and challenges of CMMI and software development integration within the context of Agile project management. Emphasizing the enhancement of Agile project management maturity, the research delves into the role of CMMI, particularly CMMI-DEV, as a pivotal element in Software Process Improvement (SPI) models tailored to Agile environments. The study's novelty lies in its systematic and in-depth investigation of CMMI's integration with Agile project management methodologies, a critical yet underexplored area in the existing literature. Addressing the urgency highlighted by global trends of resource inefficiencies and project management challenges, this research offers timely insights for both academia and industry. This study also categorizes key benefits while identifying prevalent challenges, such as resource constraints and organizational resistance. Additionally, this research also suggests solutions and improvements to these challenges. By offering a comprehensive evaluation, the research significantly advances the understanding of the complexities and potential of CMMI and Agile project management integration. It provides valuable insights for practical applications in organizational settings, emphasizing the potential of integrating structured models like CMMI-DEV with Agile project management methodologies. This integration is essential for enhancing project management maturity, marking a significant step forward in academic research and practical applications in this vital domain.