Flame-resistant composite materials containing carbon nanotubes are described herein. The flame-resistant composite materials contain an outer layer and at least one inner layer, containing a first polymer matrix and a second polymer matrix, respectively. The outer layer has an exterior surface and a first carbon nanotube-infused fiber material that contains a first fiber material and a first plurality of carbon nanotubes greater than about 50 muetaiota in length. In some embodiments, the at least one inner layer also contains a second fiber material and/or a second carbon nanotube-infused fiber material containing a second fiber material and a second plurality of carbon nanotubes. When present, the second plurality of carbon nanotubes are generally shorter in length than the first plurality of carbon nanotubes. Alignment of the carbon nanotubes in the outer layer can transfer heat away from the composite material's inner layer(s). Flame-resistant articles containing carbon nanotube- infused fiber materials are also described.