In　this　work,　a　high-performance　Mg-8.4Gd-4.4Li-3.5Y-1.4Zn　(wt%)　alloy　was　successfully　prepared　by　low-temperature　hot　extrusion.　The　studied　alloy　has　a　TYS　of　295　±　1　MPa　and　an　EL　of　2.5　%±0.2　%　at　room　temperature,　159　±　8　MPa　and　15.9　%±1.4　%　at　150　°C,　and　143　±　4　MPa　and　19.8　%±1.8　%　at　200　°C.　The　high　performance　at　temperatures　up　to　200　°C　is　attributed　to　the　dispersion　strengthening　of　three　Mg3RE　phase　variants,　the　solid　solution　strengthening　of　alloying　elements　and　the　bimodal　structure　consisting　of　fine　DRXed　grains　with　random　texture　and　coarse　un-DRXed　grains　with　basal　texture.　A　novel　island　shaped　β1R　phase　(FCC,　a　=　0.78　nm)　with　a　size　of　30　nm–100　nm　is　observed　in　the　studied　alloy.　The　β1R　phase　precipitates　on　the　{11¯00}α　prismatic　planes.　The　strain-induced,　dislocation-assisted　dynamic　precipitation　during　low-temperature　hot　extrusion　is　responsible　for　the　formation　of　the　β1R　phase.　The　growth　of　the　β1R　phase　is　owing　to　the　aid　of　the　formation　and　transformation　of　zig-zag　structures.　The　basal　slip　of　dislocations　is　the　dominate　deformation　mechanism　of　the　studied　alloy　in　the　early　stage　of　tensile　deformation　at　room　temperature,　while　non-basal　slip　of　and　dislocations　at　200　°C.　Due　to　the　strong　interaction　between　β1R　precipitates　and　dislocations,　the　densely　distributed　β1R　precipitates　significantly　improve　the　mechanical　properties　via　the　Orowan　strengthening　both　at　room　temperature　and　elevated　temperatures.　©　2021