AbstractHydrogels containing a large amount of water have been widely studied as fireproof materials. However, the organic networks that composed the gel easily burns as water evaporates. In this work, the widely used intumescent flame‐retardant ammonium polyphosphate was modified by carbon–carbon double bonds (abbreviated as MAPP) and introduced in alginate/poly (acrylamide‐co‐stearyl methacrylate) [alginate/P(AAm‐co‐SMA)] hydrogel by free radical polymerization. The resultant MAPP@alginate/P(AAm‐co‐SMA) hydrogels show good mechanical strength of 650 kPa and healing efficiency of 80%. Thermal analysis and thermal protective performance tests indicate that the MAPP particles improve the thermal stability and heat resistance of gel. The fireproof test shows that the MAPP@alginate/P(AAm‐co‐SMA) gel composite shows twice of fire proof time over the pure hydrogels.