A kind of commercial hybrid carrageenan (HC)/agarose composite sponge containing κ‐, μ‐, ι‐, and ν‐carrageenan, which could turn into hydrogel and release carrageenan at human body temperature was fabricated for immune stimulation and modulation. Release behavior demonstrated that the hybrid carrageenan contained sponge was mechanically stable and could release carrageenan constantly. RT‐PCR and ELISA experiments showed that the leaching liquor of the sponge could stimulate RAW264.7 from M0 state to a polarized state by secreting more anti‐inflammatory factor IL‐10 than pro‐inflammatory ones, such as, IL‐6 and TNF‐α. Transwell experiments also indicated that the leaching liquor could promote the proliferation of NIH‐3T3 by stimulating RAW264.7 of M0 state after 7 days. Results of particle size and intracellular concentration analyses suggested that the released carrageenan might enter into the cellular interior of RAW264.7 in the form of microgels or protein complexes. The sponge would be a promising candidate for skin wound dressing.