Abstract: Results of studying different-scale ionospheric irregularities on the basis of multi-instrumental data, obtained in the East Siberian region of Russia during the geomagnetic storm of May 27–28, 2017, are presented. Spatial inhomogeneities of electron density in the ionosphere were observed through data from ground-based receivers of signals of global navigational satellite systems and on the basis of direct measurements of electron density in low-orbit satellites. An intense radio aurora was seen in UHF radar data just after the initial phase of geomagnetic storm. At the same time, we recorded fluctuations of the total electron content from data of GPS receivers and the presence of E-layer irregularities by data of the ionosonde in Norilsk. The time of irregularity recording by different instruments is consistent with the spatiotemporal changes in field-aligned currents of the second zone, obtained from data of AMPERE low-orbit satellite system.