Carbon aerogels (CAs) have attracted attention in thermal insulation. However, the traditional sol–gel method for preparing them involves time-consuming solvent exchange and rigorous supercritical drying processes, and the obtained CAs are brittle and crumble easily. To address these problems, a carbon fibre-reinforced carbon aerogel (CF/CA) was prepared via combining a resorcinol–furfural (RF) gel containing a salt (ZnCl₂) with polyacrylonitrile (PAN) fiber felt. The CF/CA not only has low thermal conductivity (0.6904 W m⁻¹ K⁻¹) even at an ultra-high temperature of 1800 °C in an argon atmosphere but also exhibits relatively high compressive strength (6.10 MPa, 10% ε) and a low density of 0.68 g cm⁻³. The CF/CAs can be used as ultrahigh-temperature thermal insulators (under inert atmospheres or vacuum) in thermal protection systems such as space vehicles or industrial high temperature furnaces. Our novel strategy may lead to lower-cost and large scale industrial processes of CF/CAs.