  Vortex fiber nulling (VFN) is a technique for detecting and characterizing
faint companions at small separations from their host star. A near-infrared
($\sim2.3 \mu$m) VFN demonstrator mode was deployed on the Keck Planet Imager
and Characterizer (KPIC) instrument at the Keck Observatory and presented
earlier. In this paper, we present the first VFN companion detections. Three
targets, HIP 21543 Ab, HIP 94666 Ab, and HIP 50319 B, were detected with
host-companion flux ratios between 70 and 430 at and within one diffraction
beamwidth ($\lambda/D$). We complement the spectra from KPIC VFN with flux
ratio and position measurements from the CHARA Array to validate the VFN
results and provide a more complete characterization of the targets. This paper
reports the first direct detection of these three M dwarf companions, yielding
their first spectra and flux ratios. Our observations provide measurements of
bulk properties such as effective temperatures, radial velocities, and
v$\sin{i}$, and verify the accuracy of the published orbits. These detections
corroborate earlier predictions of the KPIC VFN performance, demonstrating that
the instrument mode is ready for science observations.
