  Whether binary neutron star mergers are the only astrophysical site of rapid
neutron-capture process ($r$-process) nucleosynthesis remains unknown.
Collapsars associated with long gamma-ray bursts (GRBs) and hypernovae are
promising candidates. Simulations have shown that outflows from collapsar
accretion disks can produce enough $r$-process materials to explain the
abundances in the universe. However, there is no observational evidence to
confirm this result at present. SN 2020bvc is a broad-lined type Ic (Ic-BL)
supernova (SN) possibly associated with a low-luminosity GRB. Based on
semi-analytic SN emission models with and without $r$-process materials, we
perform a fitting to the multi-band light curves and photospheric velocities of
SN 2020bvc. We find that in a $r$-process-enriched model the mixing of
$r$-process materials slows down the photospheric recession and therefore
matches the velocity evolution better. The fitting results show that
$r$-process materials with mass of $\approx0.36~M_\odot$ and opacity of
$\approx4~\rm cm^2~g^{-1}$ is needed to mix with about half of the SN ejecta.
Our fitting results are weakly dependent on the nebular emission. Future
statistical analysis of a sample of type Ic-BL SNe helps us understand the
contribution of collapsars to the $r$-process abundance.
