Secure IoT device update

The disclosed technology is generally directed to updating of applications, firmware and/or other software on IoT devices. In one example of the technology, a request that is associated with a requested update is communicated from a normal world of a first application processor to a secure world of the first application processor. The secure world validates the requested update. Instructions associated with the validated update are communicated from the secure world to the normal world. Image requests are sent from the normal world to a cloud service for image binaries associated with the validated update. The secure world receives the requested image binaries from the cloud service. The secure world writes the received image binaries to memory, and validates the written image binaries.