An embodiment of a geiger-mode avalanche photodiode includes: a body of semiconductor material, having a first surface and a second surface; a cathode region of a first type of conductivity, which extends within the body; and an anode region of a second type of conductivity, which extends within the cathode region and faces the first surface, the anode and cathode regions defining a junction. The anode region includes at least two subregions, which extend at a distance apart within the cathode region starting from the first surface, and delimit at least one gap housing a portion of the cathode region, the maximum width of the gap and the levels of doping of the two subregions and of the cathode region being such that, by biasing the junction at a breakdown voltage, a first depleted region occupies completely the portion of the cathode region within the gap.