Almost　all　marine　organisms　contain　both　inorganic　and　organic　mercury,　and　thus　it　is　extremely　important　to　determine　mercury　species　in　seafood　to　objectively　and　scientifically　assess　the　health　risk　posed　by　mercury.　We　herein　developed　a　broad-applicability　microwave-assisted　extraction　method　and　a　robust　ion　chromatography-inductively　coupled　plasma　mass　spectrometry　(IC-ICP-MS)　method　for　the　speciation　analysis　of　mercury　in　various　seafood　samples　including　seaweeds,　fishes　and　shellfishes.　The　extraction　method　has　broad　adaptability,　it　can　be　used　to　simultaneously　extract　mercury　species　from　various　seafood　samples　including　seaweeds,　fishes　and　shellfishes　without　altering　the　chemical　species　of　mercury,　with　an　extraction　efficiency　＞90%.　Especially,　the　seafood　extract　obtained　with　the　extraction　method　can　be　directly　used　for　the　following　IC-ICP-MS　determination　of　mercury　species　without　additional　pretreatment.　The　IC-ICP-MS　method　used　low-cost　cation　guard　columns　as　the　separation　column,　and　has　an　instrument　detection　limit　of　0.02-0.05　ng　mL−1　for　Hg2+,　CH3Hg+　and　C2H5Hg+.　The　developed　extraction　and　IC-ICP-MS　methods　have　been　successfully　used　to　determine　Hg2+,　CH3Hg+　and　C2H5Hg+　in　various　seaweeds,　fishes　and　shellfishes　without　the　matrix　effect,　with　a　method　detection　limit　of　2.4-6.0　ng　g−1　dried　weight,　a　recovery　of　92-105%,　and　a　relative　standard　deviation　(RSD,　n　=　5)　of　less　than　or　equal　to　6%.　The　success　of　this　study　offers　a　reliable　and　universal　approach　for　the　speciation　analysis　of　mercury　in　seafood,　which　may　provide　the　database　for　objectively　assessing　the　health　risks　of　mercury　in　seafood　and　ensuring　the　safety　of　consumption　of　seafood.　©　2023　The　Royal　Society　of　Chemistry.