This study analyzes the importance of the legal dimension in Public-Private Partnerships (PPPs), emphasizing its impact on attracting investments and project effectiveness. Using a qualitative approach, a theoretical review was conducted through a bibliographic study. The selected literature was analyzed using content analysis, with manual coding of thematic categories such as legal security, legislative alignment and impacts on project efficiency. Legal security attracts companies to PPPs, as risk sharing and compliance with current legislation are critical factors for the success of projects. Robust and well-formulated legislation is the backbone of Public-Private Partnerships. It provides the necessary structure for risk sharing, ensures transparency and legal compliance, and guarantees financial compensation mechanisms that protect the interests of both sectors. The results show that early actions can increase project efficiency, quality and confidence, reducing risk uncertainty. The study expands the research by showing that paying attention to legal elements reduces problems in relationships between public and private partners. It is essential to align objectives and share risks from the beginning of the project. A security and efficiency framework is provided by current legislation, such as PPP Law 11,079/2004. Future legislation, such as Bill 7,063/2017, should increase the use of PPPs and reduce transaction costs.