The $\Xi cc++\to \Xi c\prime +\pi +$ decay is observed using proton-proton collisions collected by the LHCb experiment at a centre-of-mass energy of $13\mathrm{Te}V$, corresponding to an integrated luminosity of $5.4\mathrm{fb}-1$. The $\Xi cc++\to \Xi c\prime +\pi +$ decay is reconstructed partially, where the photon from the $\Xi c\prime +\to \Xi c+\gamma$ decay is not reconstructed and the $pK-\pi +$ final state of the $\Xi c+$ baryon is employed. The $\Xi cc++\to \Xi c\prime +\pi +$ branching fraction relative to that of the $\Xi cc++\to \Xi c+\pi +$ decay is measured to be $1.41\pm 0.17\pm 0.10$, where the first uncertainty is statistical and the second systematic.