We say that a graph G is anti-Ramsey for a graph H if any proper edge-colouring of G yields a rainbow copy of H, i.e. a copy of H whose edges all receive different colours. In this work we determine the threshold at which the binomial random graph becomes anti-Ramsey for any fixed graph H, given that H is sufficiently dense. Our proof employs a graph decomposition lemma in the style of the Nine Dragon Tree theorem that may be of independent interest.