In this modern world, with continuous rise of vehicle ownership and usage, parking space has become a big challenge in companies, institutions and major cities as a whole. Research is on-going in this area to help solve this ubiquitous problem by the use of smart parking systems. Currently, extensive use of wireless technology applications to help solve the parking issue shows that digital data dissemination is the way to go. Infra-red (IR) technology which is a Wireless Sensor technology has attracted increased attention over the years due to its enormous application potential in diverse fields and also its potential of been an efficient and cost-effective alternative solution. This paper proposes an Authorized car parking alert system which provides advanced features like remote parking monitoring and parking reservation mechanism. The authorised car parking alert system is a typical internet of things (IoT) application that is developed using IR technology to provide services to users and parking owners of a smart institution and city. The paper describes the overall system design to implementation in the view point of sensor networks. Consideration is made of a smart parking infrastructure where sensors are laid down on the parking spots to detect car presence and IR readers are embedded into parking slot to identify cars and help in the arrangement of the parking area. Devices are endowed with wireless communication capabilities for reporting to the ground where the situation recognition is performed and also prevent unauthorized cars from entering or parking at any unassigned area.