Sonic Lost World (ソニックロストワールド Sonikku Rosuto Wārudo?) is a platforming video game in the Sonic the Hedgehog series. The game was released exclusively for the Wii U and Nintendo 3DS on 18 October 2013 in Europe, 24 October in Japan and 29 October in North America.

The game follows Sonic the Hedgehog and Tails the Fox exploring a mysterious floating continent known as "Lost Hex" after it is discovered that Dr. Eggman is planning to build a machine on the continent to drain the planet of all its energy, making it easier to conquer. They soon find that Dr. Eggman has enslaved a group of Aliens known as The Deadly Six, a gang of demon-like aliens known as Zeti, with super-human strength, speed, durability, the power of flight and the electromagnetic manipulation allowing them to control energy and the robots in Eggman's Army. The Deadly Six consist of Zazz, Zomom, Zeena, Zor, Master Zik, and their leader Zavok, who are each tasked with defeating Sonic.

Game play wise, the game is a 3D platformer that uses a new "Parkour System" allowing Sonic to climb walls, vault, jump from wall-to-wall, and sidestep to navigate the irregular shape and structure of Lost Hex. The game also features the return of the Wisps and their associated color powers, plus several new Wisps like Black Bomb and Gray Quake.

The 3DS and Wii U versions of the game are considered two separate games rather than two different ports of the same game. Each game has exclusive wisps, different level and boss design, different controls, and Different Multiplayer experiences.