New vectorlike quarks have been proposed in many scenarios of new physics beyond the Standard Model that address the hierarchy problem, which can be potentially discovered at the Large Hadron Collider~(LHC). Based on a model-independent framework, we propose to search for the vectorlike $B$-quark~(VLQ-$B$) and concentrate on resonant production via $b$-gluon fusion through chromomagnetic interactions. We then explore the possible signals of the VLQ-$B$ through the $B\to tW$ decay mode at the 14 TeV LHC. After a fast simulation of signal and background events, the $2\sigma$ excluded regions and the $5\sigma$ discovery reach in the parameter plane of $\kappa_{B}-m_B$, are, respectively, obtained at the LHC with 300~(3000) fb$^{-1}$ of integrated luminosity in the dilepton final states.