The current research uses the principles of reinforcement theory of motivation and self-determination theory and investigates how motivation and rewards impact on job performance of employees. Motivation and rewards are examined from intrinsic and extrinsic perspectives, while job performance is measured from the task and contextual performance aspects. The mediating effect of job satisfaction has also been investigated between motivation, rewards, and job performance. Using five points Likert scale, the researchers collected data from the managerial and non-managerial staff working in manufacturing and services firms. Non- probability convenience sampling technique was followed to collect 422 empirical responses. The collected data were analyzed using the structural equation modeling technique. The results indicated that reward and motivation affect employee job performance positively significantly. However, the dimensional analysis indicated an insignificant impact of intrinsic and extrinsic motivation on contextual performance. Besides, the findings substantiate that the relationship between rewards, motivation, and employees’ job performance depends on job satisfaction. The current research provides valuable insights to senior management of manufacturing and services firms on how they can enhance their employees' job satisfaction and performance by following different motivational and reward approaches in different size firms.