Aims　We　aim　to　study　the　effect　of　role　overload,　work　engagement　and　perceived　organisational　support　on　nurses＇　job　performance,　including　task　performance,　interpersonal　facilitation　and　job　dedication.　Background　Many　nurses　have　suffered　from　role　overload　at　work　during　the　COVID-19　pandemic.　However,　the　investigations　of　the　influence　mechanisms　and　boundary　conditions　through　and　under　which　role　overload　is　associated　with　job　performance　have　shown　inconsistent　results.　Methods　A　total　of　595　Chinese　nurses　were　studied　from　November　2020　to　February　2021.　Confirmatory　factor　analysis,　maximum　likelihood　estimation　and　bootstrapping　analysis　were　used　to　test　the　mediating　process　and　the　moderating　effect.　Results　Work　engagement　partly　mediated　the　relationships　of　role　overload　with　task　performance　(beta　=　-.253,　p　＜　.001,　95%　CI:　[-.315,　-.204])　and　interpersonal　facilitation　(beta　=　-.202,　p　＜　.001,　95%　CI:　[-.261,　-.145]);　work　engagement　also　fully　mediated　the　relationship　between　role　overload　and　job　dedication　(beta　=　-.239,　p　＜　.001,　95%　CI:　[-.302,　-.186]).　Perceived　organisational　support　moderated　the　relationships　of　role　overload　with　task　performance,　interpersonal　facilitation　and　work　dedication　(beta　=　-.171,　p　＜　.001,　beta　=　-.154,　p　＜　.001　and　beta　=　-.175,　p　＜　.001,　respectively).　Conclusions　Work　engagement　is　the　linchpin　linking　role　overload　to　distal　outcomes　of　job　performance.　Perceived　organisational　support　mitigates　the　ways　in　which　role　overload　undermines　job　performance.　Implications　for　Nursing　Management　Hospital　administrators　can　minimize　the　effects　of　role　overload　and　create　a　more　supportive　organisational　environment　to　promote　the　job　performance　of　nurses.