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• Mastocarpus stellatus was successfully processed by microwave hydrodiffusion and gravity (MHG). • MHG allowed recovering hybrid carrageenans and bioactives reducing extraction time to 1/3. • Extraction yields were comparable to those in red algae with conventional techniques. • Extracted biopolymers improved gelling properties of their commercial counterparts. • MHG extracts were adequately added to functional hydrogels with potential food applications. This work deals with the use of microwave hydrodiffusion and gravity (MHG) for the recovery of hybrid carrageenans with specific mechanical features together with bioactive compounds. For this purpose, Mastocarpus stellatus red seaweed was used as raw material and the most adequate MHG processing conditions were studied. The physicochemical properties of the algae and the corresponding biopolymers, the fundamental characterisation of the bioactive compounds from the extracts (antioxidant capacity, sulfate content, protein content, among others) and the rheological features of the formulated gels were analysed. Results indicated that MHG is an adequate technique for obtaining functional extracts with potential applications in the food and non-food fields. Hybrid carrageenans with a wide range of viscoelastic features were recovered by MHG, saving time compared to conventional methods. The yields obtained for the recovered hybrid carrageenans and bioactive fractions were comparable to those obtained in red algae with conventional techniques. [ABSTRACT FROM AUTHOR]