The 21st-century city is a complex, dynamic organism facing unprecedented challenges from climate change, rapid urbanization, and growing demands for equity and livability. Traditional urban design methodologies, often slow and siloed, are increasingly inadequate for this task. This paper posits that Artificial Intelligence represents a fundamental paradigm shift, moving urban design from a reactive, intuition-based practice to a proactive, evidence-driven science of systemic interdependencies. The paper examines AI’s dual role as a powerful analytical tool for understanding urban complexity and as a generative partner in creating optimized, sustainable forms. The discussion traces the conceptual evolution from data-centric "Smart Urbanism" to the adaptive, predictive, and generative frameworks of "AI Urbanism" and "AI-aided Urbanism." A core focus is placed on how these frameworks can prioritize human-centered outcomes, notably through the nascent field of emotional geospatial analysis, which seeks to quantify and design for the psychological experience of place. Crucially, the paper dedicates significant analysis to the critical ethical imperatives of this transition—addressing issues of algorithmic bias, data sovereignty, transparency, and the indispensable role of the "human-in-the-loop" to ensure that the cities shaped by AI are equitable, democratic, and truly for people.