It is impossible to imagine our lives with smart phones or mobile devices. Mobile phones are not just a means for communication today, people use mobile phone devices for entertainment as well as business. We store sensitive data in our smart phones, perform digital transactions and lot of other things. Due to the portable nature, these mobile devices are easy to be stolen or lost. Since these devices are an integral part of our life and contains sensitive personal and business data, it is very important to prevent their theft. There are several solutions available to prevent the mobile theft, but they have some limitations like data security, leakage of personal information or misuse of data by a malicious third party. In order to overcome these limitations, we propose a blockchain based mobile theft prevention system. The proposed solution uses blockchain and smart contracts for authentication, storing user data and tracking of mobile device. By introducing the blockchain in the system, we make it much more secure from user’s privacy and security point of view. The proposed system not only provides security and privacy to the user but also a platform to make the sale/purchase of the device and transfer the ownership to the other user as well.