A method and apparatus for controlling message schema and size for internet-of-things (IoT) devices is provided. An exemplary method includes determining if a cost function for a new schema and message size combination is less than the cost function of a current schema and message size combination by calculating the cost function for each of a plurality of schema and message size combinations, and determining if the cost function for one of the plurality of schema and message size combinations is lower than a current schema and message size combination.