From about 4 million hadronic $\rm Z^0$ decays recorded by the OPAL detector on and near to the $\rm Z^0$ resonance, we select a sample of more than $570\, 000$ inclusively reconstructed B mesons. Orbitally-excited mesons ${\rm B}^*_J$ are reconstructed using $\rm B\pi^\pm$ combinations. Independently, $\rm B^*$ mesons are reconstructed using the decay $\rm B^*\rightarrow B\gamma$. The selected $\rm B^*$ candidates are used to obtain samples enriched or depleted in the decay ${\rm B}^*_J\rightarrow\rm B^*\pi^\pm (X)$, where (X) refers to decay modes with or without additional accompanying decay particles. From the number of signal candidates in the $\rm B\pi^\pm$ mass spectra of these two samples, we perform the first measurement of the branching ratio of orbitally-excited B mesons decaying into $\rm B^*\pi(X)$: \[ {\rm BR(B}^*_J\rightarrow\rm B^*\pi(X)) = 0.85^{\,+0.26}_{\,-0.27} \pm 0.12 \, , \] where the first error is statistical and the second systematic.