Due　to　the　excellent　strength-ductility　combination　and　great　potential　for　applications　in　industry,　medium-entropy　alloys　(MEAS)　with　a　single　face-centered　cubic　structure　(FCC)　have　attracted　great　research　interests.　However,　the　strength　of　FCC　MEAs　is　inadequate　to　meet　the　increasing　requirements　as　structural　materials　served　at　extreme　conditions.　Herein,　we　report　a　strategy　to　obtain　FCC　structured　(CoCrNi)100-xVx　alloys　with　superior　properties　at　both　room　or　cryogenic　temperatures.　By　introducing　V　element　and　adjusting　its　content,　the　strength　of　the　alloys　is　significantly　enhanced,　though　with　a　decrease　in　ductility.　Nevertheless,　at　the　cryogenic　temperature　of　77　K,　all　alloys　exhibit　a　synergistic　improvement　in　both　strength　and　ductility　compared　to　room　temperature.　Microstructural　analysis　indicates　that　the　enhanced　strength　at　room　or　cryogenic　temperature　is　mainly　due　to　the　introduction　of　dense　twinning　into　the　alloys　through　rolling　and　recrystallization　processes.　In　addition,　the　dense　twinning　also　promotes　plane　slip,　provides　additional　work　hardening,　delays　the　occurrence　of　necking,　and　thus　enhances　the　ductility.　©　2025　Elsevier　B.V.