A high-entropy alloy, Al0.5CrCoFeNi, was produced using laser powder-bed fusion (L-PBF) additive manufacturing, resulting in a nano-bridged honeycomb microstructure with a face-centered cubic (fcc) matrix and an ordered body-centered cubic B2 phase. This unique microstructure provides both high strength and excellent fracture toughness. The B2 phase, combined with high dislocation density and solid-solution strengthening, contributes to the alloy's strength, while the nanobridges of dislocations allow for dislocation movement away from the crack tip, enhancing toughness. The alloy exhibits a yield strength of ~729 MPa at 298 K and ~942 MPa at 77 K, with a fracture toughness of ~306 MPa√m at 298 K and ~290 MPa√m at 77 K. The combination of high strength and fracture toughness is achieved through intrinsic toughening mechanisms, such as dislocation movement and nano-twinning, rather than extrinsic mechanisms. The microstructure also shows improved damage tolerance compared to conventional alloys. The study highlights the potential of additive manufacturing for designing materials with optimal strength and toughness, demonstrating the effectiveness of a "bottom-up" approach in achieving superior mechanical properties.A high-entropy alloy, Al0.5CrCoFeNi, was produced using laser powder-bed fusion (L-PBF) additive manufacturing, resulting in a nano-bridged honeycomb microstructure with a face-centered cubic (fcc) matrix and an ordered body-centered cubic B2 phase. This unique microstructure provides both high strength and excellent fracture toughness. The B2 phase, combined with high dislocation density and solid-solution strengthening, contributes to the alloy's strength, while the nanobridges of dislocations allow for dislocation movement away from the crack tip, enhancing toughness. The alloy exhibits a yield strength of ~729 MPa at 298 K and ~942 MPa at 77 K, with a fracture toughness of ~306 MPa√m at 298 K and ~290 MPa√m at 77 K. The combination of high strength and fracture toughness is achieved through intrinsic toughening mechanisms, such as dislocation movement and nano-twinning, rather than extrinsic mechanisms. The microstructure also shows improved damage tolerance compared to conventional alloys. The study highlights the potential of additive manufacturing for designing materials with optimal strength and toughness, demonstrating the effectiveness of a "bottom-up" approach in achieving superior mechanical properties.