The objective of this article is to design, develop, and evaluate an Internet of Things (IoT)-based serious gaming platform for children with autism spectrum disorder. The platform aims to improve the children's cognitive skills. To attain this research objective, first, a conceptual framework for developing the gaming platform was proposed. Then, the conceptual ideas were materialized by developing three games (a puzzle game, a function card game, and a road crossing game) to be included in the gaming platform, which also incorporated a mobile application and three hardware systems. The hardware platform was used to play the game, and the mobile application was used to select, control, manage, and store the gaming performance and visualize players' progress. The proposed gaming platform was evaluated with 15 special needs children. We found that the gaming platform was usable, effective, and useful for the children on the spectrum and noticeably contributed to improving their cognitive skills.