A　novel　flow-through　multiplexed　immunoassay　protocol　for　simultaneous　electrochemical　determination　of　carcinoembryonic　(CEA)　and　alpha-fetoprotein　(AFP)　in　biological　fluids　was　designed　using　biofunctionalized　magnetic　graphene　nanosheets　(MGO)　as　immunosensing　probes　and　multifunctional　nanogold　hollow　microspheres　(GHS)　as　distinguishable　signal　tags.　The　probes　were　fabricated　by　means　of　co-immobilization　of　primary　anti-CEA　(Ab(1))　and　anti-AFP　(Ab(2))　antibodies　on　the　Fe3O4　nanoparticle-coated　graphene　nanosheets　(MGO-Ab(1,2)).　The　reverse-micelle　method　was　used　for　the　synthesis　of　distinguishable　signal　tags　by　encapsulation　of　horseradish　peroxide　(HRP)-thionine　and　HRP-ferrocene　into　nanogold　hollow　microspheres,　respectively,　which　were　utilized　as　labels　of　the　corresponding　GHS-Ab(1)　and　GHS-Ab(2).　A　sandwich-type　immunoassay　format　was　employed　for　the　online　detection　of　CEA　and　AFP　by　coupling　a　flow-through　detection　cell　with　an　external　magnet.　The　assay　was　based　on　the　catalytic　reduction　of　H2O2　at　the　various　peak　potentials　in　the　presence　of　the　corresponding　mediators.　Experimental　results　revealed　that　the　multiplexed　electrochemical　immunoassay　enabled　the　simultaneous　monitoring　of　AFP　and　CEA　in　a　single　run　with　wide　working　ranges　of　0.01-200　ng　mL(-1)　for　AFP　and　0.01-80　ng　mL(-1)　for　CEA.　The　detection　limits　(LODs)　for　both　analytes　at　1.0　pg　mL(-1)　(at　3s(B))　were　very　low.　No　obvious　nonspecific　adsorption　and　cross-talk　were　observed　during　a　series.　of　analyses　to　detect　target　analytes.　Intraassay　and　interassay　coefficients　of　variation　were　＜　10%.　Importantly,　the　methodology　was　evaluated　for　the　analysis　of　clinical　serum　specimens,　receiving　a　good　correlation　between　the　flow-through　multiplexed　electrochemical　immunoassay　and　an　electrochemiluminescence　method　as　a　reference.