Cybersecurity has become a critical concern in the digital world, demanding robust and intelligent systems capable of defending against increasingly complex and evolving threats. This paper comprehensively explores the intersection between machine learning (ML) and cybersecurity, highlighting how data-driven approaches are reshaping threat detection, prevention, and response mechanisms. We provide an in-depth overview of core ML paradigms and analyze their relevance and effectiveness in various cybersecurity applications. A systematic literature review was conducted using major academic databases including IEEE Xplore, ACM Digital Library, SpringerLink, and ScienceDirect, covering peer-reviewed journal articles and conference papers published primarily between 2018 and 2025. Studies were selected based on relevance to ML-driven cybersecurity applications, methodological rigor, and demonstrated practical impact, while works lacking empirical validation or cybersecurity relevance were excluded. The review examines core ML paradigms: supervised, unsupervised, semi-supervised, and reinforcement learning, and analyzes their effectiveness across key cybersecurity domains such as malware detection, phishing detection, financial crime detection, anomaly detection, mobile security, and intrusion detection systems. We review prominent ML algorithms and detail their application in detecting malicious behavior across network traffic, system logs, and user activities. In addition, we survey open-source tools and platforms commonly used in cybersecurity-focused ML research and practice. The practical component of the paper showcases real-world use cases, including spam filtering, fraud detection, and endpoint security, illustrating how organizations can integrate ML techniques into operational security infrastructures. The paper also investigates the challenges and limitations of applying ML in cybersecurity, including adversarial ML, data imbalance, concept drift, and model interpretability. Finally, emerging research directions such as explainable AI, edge AI, federated learning, and quantum ML are discussed as promising avenues for advancing robust, transparent, and future-ready cybersecurity solutions. By bridging theoretical foundations with real-world practices, this paper aims to equip researchers, practitioners, and decision-makers with a holistic understanding of the capabilities, tools, and future potential of ML in advancing cybersecurity resilience.