Planetary magnetic fields act as protective barriers, shielding a planet’s atmosphere and surface from energetic charged particles originating from its parent star and outer space. During its fourth flyby of Mercury on 4 September 2024, the ESA/JAXA BepiColombo mission passed within just 165 km of the planet’s surface. This close approach coincided with the elevated fluxes of high-energy charged solar particles, providing an opportunity to study shielding processes of a planet in close proximity to its star. Here, utilizing observations from the Solar Intensity X-Ray and Particle Spectrometer (SIXS) onboard BepiColombo, we investigate the penetration of high energy particles from the Sun into Mercury’s magnetosphere. The variations in energetic particle fluxes depend on the particle type, direction and energy. Our analysis reveals that the disappearance of protons is related to magnetic shadowing by the planet, while electrons dropouts occur due to a wide magnetic loss cone. These findings show that sustained high-energy particle precipitation can occur during solar energetic particle events on weakly magnetized rocky planets orbiting close to their parent star. Such processes probably play a significant role in regolith alteration and exospheric variability, with broader implications for surface geochemistry and potential habitability.