This chapter examines the intersection of FinTech, AI, blockchain, and DeFi, exploring their implications, challenges, and regulatory considerations. It traces the evolution of AI, covering subsets such as ML and DL, as well as emerging technologies such as NLP and LLMs. The chapter highlights the transformative impact of AI on finance, including predictive analytics, algorithmic trading, credit scoring, fraud detection, and experimental applications of generative AI. DeFi challenges centralized financial systems by enabling decentralized payments, asset tokenization, and data verification. The chapter examines blockchain-driven innovations, including cryptocurrencies, stable coins, and smart contracts, and contrasts their decentralized potential with centralized exchanges and existing regulatory frameworks. It also looks at institutional resistance to DeFi and the regulatory hurdles that limit widespread adoption. Regulatory challenges remain a central theme, particularly the lack of global standards for AI and crypto assets. The chapter compares regulatory approaches in the EU, the US, and China, analyzing frameworks such as the EU AI Act and the Markets in Crypto Assets Regulation. It highlights the difficulties of regulating decentralized systems and the slow adaptation of financial authorities to emerging technologies. Finally, the chapter envisions a future in which FinTech innovations continue to disrupt traditional finance, depending on solving AI accountability issues, managing technological complexity, and overcoming institutional resistance to DeFi. It advocates for collaboration between legal and technological experts to fully realize FinTech's potential for societal benefit.