Group　III-VI　family　MX　(M　=　Ga　and　In,　and　X　=　S,　Se,　and　Te)　monolayers　have　attracted　global　interest　for　their　potential　applications　in　electronic　devices　due　to　their　unexpectedly　high　carrier　mobility.　Herein,　via　density　functional　theory　calculations　as　well　as　ab　initio　quantum　transport　simulations,　we　investigated　the　performance　limits　of　MX　monolayer　metal　oxide　semiconductor　field-effect　transistors　(MOSFETs)　at　the　sub-10　nm　scale.　Our　results　highlighted　that　the　MX　monolayers　possessed　good　structural　stability　and　mechanical　isotropy　with　large　ultimate　strains　and　low　Young＇s　modulus,　which　are　intensely　anticipated　in　the　next-generation　flexible　devices.　More　importantly,　the　MX　monolayer　MOSFETs　show　excellent　device　performance　under　optimal　schemes.　The　on-state　current,　delay　time,　and　power　dissipation　of　the　MX　monolayer　MOSFETs　satisfy　the　International　Technology　Roadmap　for　Semiconductors　(ITRS)　2013　requirements　for　high-performance　devices.　Interestingly,　the　sub-threshold　swings　were　in　a　very　low　range　from　68　mV　dec(-1)　to　108　mV　dec(-1),　which　indicated　the　favorable　gate　control　ability　for　fast　switching.　Therefore,　we　believe　that　our　findings　shed　light　on　the　design　and　application　of　MX　monolayer-based　MOSFETs　in　next-generation　flexible　electronic　devices.