Iota-Carrageenan (i-carrageenan) was cross-linked with Polyamidoamine hyperbranched polymer generation 1 (PAMAM). The resulted hydrogels were dried using freeze-drying technique to give new bio-based i-carrageenan aerogels. These aerogels were characterized using FT-IR and their nitrogen contents were determined using Kjeldahl method. The morphology and the surface areas of the aerogels were investigated using scanning electron microscope and Brunauer–Emmett–Teller method, respectively. The ability of the aerogels to remediate different metal ions e.g. Cr(VI), Mn(II), Co(II), Cu(II), or Cd(II) and alphanol fast blue dye (acid dye) from aqueous medium was carefully investigated. The removal investigation was conducted without pH adjustment in case of metal ions and at pH 2 for acid dye. The aerogel with the higher nitrogen content (CAR4) exhibited the highest remediation efficiency of both metal ions and acid dye.