Performance measurement in the Nigerian Public Service (NPS) is based on Annual Performance Evaluation Report (APER). The volatility of staff disposition in the NPS is to such an extent that Public Servants may work under more than two direct superiors in two or more departments within a year. This makes the APER system deficient and calls for another model that can suit any sporadic circumstance. This Paper therefore develops a new Public Service Performance Measurement Model (PSPM Model) which addresses chaotic staff disposition and provides continuous record of Public Servant's performance on a monthly basis. It is a simplified Performance Measurement System (PMS) which tasks the employee to report his monthly activities, identify key challenges and suggest ways to overcome them as well as prepare the next month's activities all of which are to be assessed by his direct superior. The Model is intended to enhance the productivity of Public Servants. However, the Model requires an automated system of operation so that all entries and submissions will be done using intranet. The Model can also be modified and adopted by private enterprises. But the Model should be used in a manner that only those who have a role in providing performance records and performance measurement can have access without the possibility to change anything once it is processed.