As of January 1, 2026, the population of the region amounted to 821,473 people, or 4.0% of the national figure (RK – 20.5 million people). Compared to last year, the number decreased by 4,096 people, or 0.5% (over the past decade, the decrease was 62.3 thousand people, or 7.1%).
The urban population prevails in the region – 63.8% (524,371 people).
The largest population is concentrated in the regional center – 277,064 people (33.7%), the smallest – in the Naurzumsky district - 8,085 people (1.0%).
There are more than 100 nationalities and nationalities living in the region. The main share of the population is Kazakhs – 44.5%, Russians – 33.5%, Ukrainians – 10.2%, Germans – 3.7%, Belarusians – 1.9%, Tatars – 1.7%, other nationalities – 4.5%.
The population density is 4.2 people per square kilometer. The cities of Kostanay, Rudny and Lisakovsk are the most densely populated, while the southern regions of the region are the least populated, with a density of 0.3 to 2.4 people per square kilometer.