It has been shown that static black hole event horizons cannot exist in time-dependent backgrounds without becoming naked singularities. In light of this, we are left with the question “how does a black hole horizon evolve in an expanding universe?” Here we offer a solution to this puzzle by showing that spherically symmetric black hole apparent horizons tend to become comoving, thus confirming the necessity of a cosmological coupling and raising intriguing possibilities for the early growth of black holes.