  The neutrinophilic two-Higgs-doublet model ($\nu$2HDM) provides a natural way
to generate tiny neutrino mass from interactions with the new doublet scalar
$\Phi_\nu$ ($H^\pm,~H,~A$) and singlet neutrinos $N_R$ of TeV scale. In this
paper, we perform detailed simulations for the lepton number violating (LNV)
signatures at LHC arising from cascade decays of the new scalars and neutrinos
with the mass order $m_{N_R}<m_{\Phi_\nu}$. Under constraints from lepton
flavor violating processes and direct collider searches, their decay properties
are explored and lead to three types of LNV signatures: $2\ell^\pm
4j+\cancel{E}_T$, $3\ell^\pm 4j+\cancel{E}_T$, and $3\ell^\pm\ell^\mp 4j$. We
find that the same-sign trilepton signature $3\ell^\pm4j+\cancel{E}_T$ is quite
unique and is the most promising discovery channel at the high-luminosity LHC.
Our analysis also yields the $95\%$ C.L. exclusion limits in the plane of the
$\Phi_\nu$ and $N_R$ masses at 13 (14) TeV LHC with an integrated luminosity of
100~(3000)/fb.
