The upper part of the peak consists of flat-lying Table Mountain sandstone and the lower slopes are formed by the Cape Granite and the Malmesbury formation, which are older Precambrian rocks.
Lion's Head is covered in fynbos (indigenous Cape vegetation), with an unusually rich biodiversity that supports a variety of small animals. Three main vegetation types can be found in this relatively small area. All three of them are endemic to the city of Cape Town and can be found nowhere else. Most of Lion's Head is covered in endangered Granite Fynbos, which fades into Peninsula Shale Renosterveld (critically endangered) on the lower slopes towards Signal Hill in the north. Right on the summit of Lion's Head however, is a tiny patch of endangered Sandstone Fynbos, a different ecosystem that is also found nearby on the top of Table Mountain.