The　laser　powder　bed　fusion　(LPBF)　manufactured　CoCrFeMnNi　high-entropy　alloy　(HEA)　presents　potential　application　at　cryogenic　temperatures,　except　for　a　relatively　low　yield　strength　(sigma　y).　In　this　work,　we　proposed　an　oversaturated　boron-doping　strategy　to　overcome　this　insufficiency.　Compared　to　the　boron-free　and　high　boron-doping　references,　the　moderate　boron-doping　LPBF　HEA　exhibits　high　strength　at　temperatures　of　77　and　298　K,　while　maintains　favourable　ductility,　corresponding　to　a　sigma　y　of　806　MPa　with　a　total　elongation　(&　varepsilon;)　of　similar　to　20%　at　298　K,　and　a　sigma　y　of　1072　MPa　with　a　&　varepsilon;　of　similar　to　12%　at　77　K,　respectively.　The　improved　mechanical　properties　are　attributed　to　the　microstructures　composed　of　refined　grains,　reduced　cell　size,　oversaturation　of　boron　and　the　formation　of　nano-sized　Cr2B　precipitates　at　cell　boundaries.　The　grain　boundary　strengthening,　precipitation　strengthening,　solid　solution　strengthening　and　dislocation　strengthening　contribute　to　the　high　sigma　y.　The　interactions　between　dislocation　slip　and　deformation　twins　with　boride　precipitates　account　for　the　enhanced　strain　hardening　and　favourable　plasticity　at　77　K.　The　results　demonstrate　an　effective　strategy　to　establish　balanced　mechanical　properties　of　LPBF　HEA,　and　provide　an　inspiration　for　future　works　aiming　to　develop　high-performance　structural　materials　over　a　wide　temperature　range.