Internet of things brings attention toward it because of its intelligent characteristics in application. In IoT, things use sensors for sharing the information between them. It mainly relies on sensors for its functioning. Though IoT produces many advantages, it still has some difficulties with respect to security of IoT applications. Machine learning is a subset of AI that can predict or take decisions based on the training data without providing external commands. ML is also emerging field in recent research. Machine learning algorithms have provided optimized solutions to many difficulties in the past, and we are trying to match the ML algorithms in the area of security in IoT applications. In this chapter, we are going to analyze the ML algorithms including Unsupervised Learning, Support Vector Machine, Supervised Learning, and reinforcement algorithms for enhancing security in IoT applications and identify suitable procedures for all the security-related issues.