An integrated circuit (IC) configurable to perform adaptive thermal ceiling control in a per-functional-block manner, an associated main circuit, an associated electronic device and an associated thermal control method are provided. The IC may include a plurality of hardware circuits arranged to perform operations of a first functional block, and at least one thermal control circuit. At least one temperature sensor is coupled with the first functional block to detect temperature and to generate at least one temperature sensing result of the first functional block. The thermal control circuit performs thermal control on the first functional block to prevent the first functional block from overheating and inducing abnormal function operations, by monitoring the temperature sensing result and by trying to prevent the temperature sensing result from exceeding first temperature upper-limit, wherein the first temperature upper-limit is configurable with respect to per-functional-block thermal operation capability of the first functional block.