It is gradually becoming a norm to find some construction trades in project sites in Nigeria being dominated by migrant artisans from other West African countries, despite the high unemployment rate in Nigeria. The magnitude and spread of these migrants in Nigerian cities deserves research attention in the effort to understand the demographic settings that encourage their influx, and the reasons why contractors often employ them. This research carried out comparative study of the factors responsible for the engagement of migrant artisans in Lagos Metropolis and Benin City, South-West and South-South Nigeria respectively. Based on data from 40 randomly selected construction sites, 20 from each of the cities; it was found that indigenous artisans were dominant on construction sites in the study area with migrant artisans constituting 19.93% in Lagos and 15.67% in Benin City. Contractors in Lagos Metropolis engage the services of migrant artisans more frequently than those in Benin City. The study further revealed that migrant artisans are mainly engaged for tiling, P.O.P. installation and plastering works in Lagos and Benin City. The migrant artisans’ ability to work for longer hours (MS= 4.03), achieve better quality of workmanship (MS= 3.94) and reduction in cost (MS= 3.92) were the most important factors accounting for their engagement in Lagos. In Benin City, better quality of workmanship (MS= 4.30), reduction in cost (MS= 4.10) and migrant artisans’ ability to work for longer hours (MS= 3.82) were the most highly rated factors. Collaboration for trade test certification between the Federal Ministry of Labour and Productivity and Polytechnics in Nigeria was recommended as a means of achieving adequate training of Nigerian artisans in order to check the increasing engagement of nationals of other countries in construction trades in Nigeria.