A leadless biostimulator has a housing including an electronics compartment, an electronics assembly mounted in the electronics compartment, a proximal electrode that disposed on and/or integrated into the housing, and an electrical feedthrough assembly. The electrical feedthrough assembly includes a distal electrode and a flange. The flange is mounted on the housing. The distal electrode is electrically isolated from the flange by an insulator and configured to be placed in contact with target tissue to which a pacing impulse is to be transmitted by the leadless biostimulator. A mount is mounted on the flange and thereby mounted on the electrical feedthrough assembly. A fixation element is mounted on the mount and configured to facilitate fixation of the leadless biostimulator to tissue of a patient.