Janus　nanoparticles　(JNPs)　refer　to　the　integration　of　two　or　more　chemically　discrepant　composites　into　one　structure　system.　Studies　into　JNPs　have　been　of　significant　interest　due　to　their　interesting　characteristics　stemming　from　their　asymmetric　structures,　which　can　integrate　different　functional　properties　and　perform　more　synergetic　functions　simultaneously.　Herein,　we　present　recent　progress　of　Janus　particles,　comprehensively　detailing　fabrication　strategies　and　applications.　First,　the　classification　of　JNPs　is　divided　into　three　blocks,　consisting　of　polymeric　composites,　inorganic　composites,　and　hybrid　polymeric/inorganic　JNPs　composites.　Then,　the　fabrication　strategies　are　alternately　summarized,　examining　self-assembly　strategy,　phase　separation　strategy,　seed-mediated　polymerization,　microfluidic　preparation　strategy,　nucleation　growth　methods,　and　masking　methods.　Finally,　various　intriguing　applications　of　JNPs　are　presented,　including　solid　surfactants　agents,　micro/nanomotors,　and　biomedical　applications　such　as　biosensing,　controlled　drug　delivery,　bioimaging,　cancer　therapy,　and　combined　theranostics.　Furthermore,　challenges　and　future　works　in　this　field　are　provided.　©　2021　American　Chemical　Society.