Warri Â· Population. Question: What is the population of Warri? Answer: Warri, Nigeria (Administrative unit: Delta) - last known population is â 663 000 (year 2015). This was 0.364% of total Nigeria population. If population growth rate would be same as in period 2006-2015 (+3.16%/year), Warri population in 2018 would be: 727 956*. Population history [1] Annual population change