  We have studied the interaction of metastable $^4$He$_2^*$ excimer molecules
with quantized vortices in superfluid $^4$He in the zero temperature limit. The
vortices were generated by either rotation or ion injection. The trapping
diameter of the molecules on quantized vortices was found to be $96\pm6$\,nm at
a pressure of 0.1\,bar and $27\pm5$\,nm at 5.0 bar. We have also demonstrated
that a moving tangle of vortices can carry the molecules through the superfluid
helium.
