The station features ten platforms that serve 20 tracks and 12 train links. It has four major entrances and exits, including west gate, east gate, south gate, and new south gate, as well as 200 exits and an underground arcade.

Shinjuku Station in Tokyo is famously recognized by the Guinness World Records as the busiest railway station in the world, serving as a massive transit "city" rather than a mere stop. In 2026, the complex spans approximately 15 acres and is a labyrinthine structure featuring 36 platforms, over 200 entrance and exit gates, and roughly 30 tracks (not including the extensive subterranean subway lines). On an average day, between 3.5 and 3.8 million people pass through its gates, making it an essential artery of Tokyo's infrastructure. The station acts as a major transfer hub for five different railway companies, including JR East, Odakyu, and Keio, and is seamlessly integrated with multiple high-rise department stores, underground shopping arcades, and a massive bus terminal (Busta Shinjuku). Navigating the station can be overwhelming even for locals, as it functions as a vertical ecosystem where millions of journeys intersect every single day.