Background:　Carotenoids　have　been　extensively　utilized　as　food　supplements,　nutraceuticals,　and　natural　colorants　for　many　years,　owing　to　their　significant　potential　in　beneficial　biological　activities　such　as　anti-oxidative　and　anti-inflammatory　effects.　Microalgae　serve　as　abundant　sources　of　diverse　carotenoids　including　beta-carotene,　astaxanthin,　and　fucoxanthin,　thereby　playing　crucial　roles　in　the　natural　carotenoids　market.　However,　understanding　of　the　bioaccessibility　and　bioavailability　of　microalgae-derived　carotenoids　in　the　gastrointestinal　tract,　their　bio-conversion　processes,　and　their　interactions　with　gut　microbiota　remains　largely　unexplored.　Scope　and　approach:　This　review　focuses　on　the　biochemical　properties　of　microalgal　carotenoids　and　their　fate　in　the　gastrointestinal　tract,　with　particular　emphasis　on　their　intricate　interplay　with　gut　microbiota.　It　also　discusses　emerging　technologies　aimed　at　enhancing　bioavailability　and　gaining　deeper　insights　into　their　interactions　with　gut　microbiota.　Key　findings　and　conclusions:　Current　studies　suggest　that　the　bioavailability　of　most　microalgal　carotenoids　is　quite　low,　with　a　portion　undergoing　conversion　within　the　gastrointestinal　tract.　The　unabsorbed　carotenoids　play　a　significant　role　in　modulating　gut　microbiota,　showing　promising　potentials　in　influencing　host　metabolism.　Emerging　technologies　such　as　nanotechnology,　foodomics,　artificial　intelligence　and　synthetic　biology　are　expected　to　revolutionize　the　study　of　microalgal　carotenoids,　providing　crucial　insights　to　facilitate　their　incorporation　into　food　products.