Transmedia Storytelling examines how successful stories move between platforms - from traditional media to digital formats - and diagnoses how platform capitalism has transformed transmedia storytelling from a democratic expansion of story worlds into a machinery of extraction. Drawing on the author's dual expertise as both producer and academic, this book analyses how storytellers create worlds that work successfully across multiple formats through an abundance of case studies. These case studies span from Marvel and Stranger Things to diverse global storytelling ecologies, including Japanese manga serialization, Korean platform co-productions, Indian epic memory traditions, and Nollywood video-film networks. Readers will discover practical tools for developing cross-platform stories, methods for creating effective story bibles and world-building, techniques for adapting characters across different media, and approaches to inclusive storytelling that acknowledge coherence as labour. The book also confronts emerging challenges, including algorithmic personalization that fragments audiences into parallel monocultures, IP financialization that transforms franchises into liquid assets, and generative AI that automates the appearance of coherence while degrading narrative causality. This book provides essential reading for undergraduate and postgraduate students undertaking digital storytelling, narrative theory, film and media production, as well as media studies classes. It also functions as a hands-on toolkit for industry professionals already working within film, gaming, and content creation.