In this paper, ultra-flyweight hydrophobic poly(m-phenylenediamine) aerogel (PmPDA) was fabricated via a simple two step approach from a poly(m-phenylenediamine) micro-spherical shell (PmPDMS). The PmPDA was first formed by freeze-drying and then cross-linked via the oxidative polymerization of surface groups following an annealing process. The PmPDA is hydrophilic before the annealing process and becomes hydrophobic (the contact angle is 103.7°) after it is annealed in air. Moreover, the obtained ultra-flyweight PmPDA (ρ = 0.8 mg cm⁻³) has a large surface area (338 m² g⁻¹), low thermal conductivity (0.0125 W m⁻¹ K⁻¹ at 25 °C) and excellent mechanical properties. Finally, the regenerated aerogels retain their original shape and ultrahigh absorption capability after more than 10 cycles, making PmPDA an ideal candidate for practical application in the absorption or removal of organics, particularly in environmental protection and pollution control.