Nigeria Customs Service operational efficiency is critical to attainment of domestic economic growth through border protection and implementation of trade policies. However, the performance of this agency has been on a declining state from 2015 to 2019. These have been attributed to the nature of work environment and motivation of employees. Therefore, the study investigated the effects of motivation on operational efficiency and work environment on employee commitment.A mixed research design was adopted with a population of 7,347 officers and men of the NCS. A sample size of 383 was computed through Krejcie and Morgan sample-size determination formula. The study adopted the stratified random sampling to select employees of NCS in Abuja and Lagos command units from three management cadres. Questionnaire and interview guide were the instrument of data collection. Response rate of 87.7% was achieved, and data was analyzed and presented through descriptive and inferential statistics. Results reveal that motivation had positive and significant effect on employee productivity in the NCS (β = 0.318, t = 7.196, p=0.000); work environment had positive and significant effect on job commitment in the NCS (β = 0.461, t = 8.777, p=0.000). The study concluded thatmotivation has significant effect on the operational efficiency, however, on the strength of the effect, revealed a weak contribution to operational efficiency. Work environment contribution to employee commitment is weak. The ripple effect of weak commitment was unethical work behaviour. The study recommended timely measures to inspire employees’ moral to perform efficiently and create enabling work environment that would boost job commitment in NCS. Keywords: Nigerian Customs Service, Work Environment, Motivation, Operational Efficiency, Public Service..