Artificial intelligence (AI) has emerged as a transformative tool in various industries, offering significant opportunities for Small and Medium Enterprises (SMEs) to improve their decision-making processes. This study systematically explores AI applications in SMEs, highlighting trends and industry-specific implementations. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR), the study synthesises insights from 97 sources, including academic and non-academic literature across multiple industries. The findings show a rising adoption of AI, particularly in generative AI, machine learning, and robotic process automation, with a notable increase in publications and real-world implementations in recent years. Geographically, AI adoption in SMEs is most pronounced in developed economies such as the United States, Germany, and China, where advanced AI infrastructure, government incentives, and digital ecosystems facilitate implementation. In emerging economies, particularly India, AI is gaining traction in manufacturing and supply chain management. Sector-wise, manufacturing exhibits the highest AI integration, leveraging robotics and machine learning for automation and optimisation, followed by the finance sector, which increasingly employs AI for fraud detection and risk assessment. This study provides an overview of key AI applications in SMEs and highlights future research directions to improve AI-driven decision-making in these enterprises.