This study examines changes in the intensity and direction of the Earth’s magnetic field using observational data from the Swarm-A satellite magnetometer during the May 2024 geomagnetic storm. This geomagnetic storm is one of the extremes occurring after several decades and is classified as G5, with a maximum Kp index of 9 and a Dst index reaching - 400 nT. In addition, the CHAOS geomagnetic field model was also employed in this study to evaluate the magnetometer measurement data, thereby facilitating the identification of anomalous data. The findings of this study show that the Earth’s magnetic field undergoes significant alterations when affected by geomagnetic activity. The CHAOS model also demonstrates considerable accuracy in evaluating the Earth’s magnetic field values as measured by the magnetometer. The error value, obtained through the calculation of Root Mean Square Error, only ranges less than 3% on the peak day of the storm, indicating that the accuracy is quite good.