  Motivated by the $R_{D^{(*)}}$ anomalies, we investigate an $\mathrm{SO}(10)$
grand unification scenario where a charge $-1/3$ scalar leptoquark ($S_1$)
remains as the only new physics candidate at the TeV scale. This leptoquark
along with the Standard Model (SM) Higgs doublet originates from the same
10-dimensional real scalar multiplet in the $\mathrm{SO}(10)$ grand unification
framework taking its mass close to the electroweak scale. We explicitly show
how the gauge coupling unification is achieved with only one intermediate
symmetry-breaking scale at which the Pati-Salam gauge group is broken into the
SM group. We investigate the phenomenological implications of our scenario and
show that an $S_1$ with a specific Yukawa texture can explain the $R_{D^{(*)}}$
anomalies. We perform a multiparameter scan considering the relevant flavour
constraints on $R_{D^{(*)}}$, $F_L{(D^*)}$, $P_\tau(D^*)$ and
$R_{K^{(*)}}^{\nu\nu}$ as well as the constraint coming from the $Z\to\tau\tau$
decay and the latest $\tau\tau$ resonance search data at the LHC. Our analysis
shows that a single leptoquark solution to the observed $R_{D^{(*)}}$ anomalies
with $S_1$ is still a viable solution.
