RhI‐catalyzed cycloisomerization of benzylallene‐alkynes produced the tricyclo[9.4.0.03,8]pentadecapentaene skeleton through a CH bond activation in good yields. A plausible reaction mechanism proceeds via oxidative addition of the acetylenic CH bond to RhI, an ene‐type cyclization to the vinylidenecarbene–RhI intermediate, and an electrophilic aromatic substitution with the vinylidenecarbene species. It