Migration acts as a growth driver for urban agglomerations, posing a difficult methodological task of its statistical accounting as well as further assessment of migration's impact on the economy of agglomerations. The paper analyzes the contribution of migration to the change in population during the intercensal interval 2010–2021 in 20 urban agglomerations of Russia identified as promising centers of economic growth by the Russian Federation Government Decree “On Approval of the Spatial Development Strategy of the Russian Federation for the period until 2025”. The study showed that the most underestimated net migration rate was demonstrated by the agglomerations of Krasnodar, distantly followed by Krasnoyarsk and the capitals (Moscow and Saint Petersburg). The leader in terms of the absolute value of unrecorded migration is the Moscow agglomeration. In Nizhny Novgorod and Perm agglomerations, indirect assessment of net migration showed that migration balance was overestimated as per the registered migration data. The identified differences in the volume of net migration between the two sources indicate the unreliability of the data, thus questioning in some urban agglomerations the alignment of the demographic potential with economic development goals.