This paper explores the transformative potential of integrating generative artificial intelligence (AI) technologies, particularly ChatGPT, into second language (L2) writing pedagogy. The paper begins by examining the evolution of L2 writing pedagogy and highlighting the strengths and limitations of each. It then discusses the integration of ChatGPT into eight stages of the writing process, such as preparation, modeling, planning, and collaborative writing, emphasizing the importance of ethical and responsible use of AI. Key challenges, including over-reliance on AI, ethical concerns, and privacy issues, are identified, with practical recommendations provided to address these concerns. Theoretical frameworks relevant to AI adoption are also discussed to offer insights into how L2 writing teachers and students might embrace AI tools. The paper concludes with research recommendations to ensure the effective and responsible integration of generative AI into L2 writing instruction.