Amanita inopinata is an intriguing species, which appeared in Europe in 1976 and propagates there slowly since then. Within the genus Amanita, it belongs to a small group of species which are very original, a.o. because they are not mycorrhizal, and which would be situated at the base of the genus phylogeny. This study presents an update on the ecology, the phenology and the distribution of A. inopinata. Its ecology, very often situated in artificial and more or less ruderalized biotopes, suggests that it is not native to Europe, and maybe not to New Zealand either, where it has also been observed. A detailed study of its progression in Europe shows that its distribution area increases either by local expansion (< 30 km) or by “big jumps” (50–300 km) and that wind would be the main vector for the latter. The expansion of A. inopinata in Europe tends to accelerate over time and we can thus consider it as an invasive species. Nevertheless, as it remains a rare species everywhere, that colonizes mainly artificial biotopes, its impact on the local mycoflora remains insignificant.