diff --git a/src/NATS.Server.Host/Program.cs b/src/NATS.Server.Host/Program.cs
index f0d614c..3febf15 100644
--- a/src/NATS.Server.Host/Program.cs
+++ b/src/NATS.Server.Host/Program.cs
@@ -139,6 +139,14 @@ using var server = new NatsServer(options, loggerFactory);
 // Register signal handlers
 server.HandleSignals();
 
+server.ReOpenLogFile = () =>
+{
+    Log.Information("Reopening log file");
+    Log.CloseAndFlush();
+    Log.Logger = logConfig.CreateLogger();
+    Log.Information("File log re-opened");
+};
+
 // Ctrl+C triggers graceful shutdown
 Console.CancelKeyPress += (_, e) =>
 {
diff --git a/src/NATS.Server/NatsServer.cs b/src/NATS.Server/NatsServer.cs
index 7bd3e76..c80fa74 100644
--- a/src/NATS.Server/NatsServer.cs
+++ b/src/NATS.Server/NatsServer.cs
@@ -61,6 +61,7 @@ public sealed class NatsServer : IMessageRouter, ISubListAccess, IDisposable
     public string ServerNKey { get; }
     public bool IsShuttingDown => Volatile.Read(ref _shutdown) != 0;
     public bool IsLameDuckMode => Volatile.Read(ref _lameDuck) != 0;
+    public Action? ReOpenLogFile { get; set; }
     public IEnumerable<NatsClient> GetClients() => _clients.Values;
 
     public Task WaitForReadyAsync() => _listeningStarted.Task;
@@ -192,7 +193,7 @@ public sealed class NatsServer : IMessageRouter, ISubListAccess, IDisposable
 
     /// <summary>
     /// Registers Unix signal handlers.
-    /// SIGTERM → shutdown, SIGUSR2 → lame duck, SIGUSR1 → log reopen (stub), SIGHUP → reload (stub).
+    /// SIGTERM → shutdown, SIGUSR2 → lame duck, SIGUSR1 → log reopen, SIGHUP → reload (stub).
     /// </summary>
     public void HandleSignals()
     {
@@ -222,7 +223,8 @@ public sealed class NatsServer : IMessageRouter, ISubListAccess, IDisposable
             _signalRegistrations.Add(PosixSignalRegistration.Create((PosixSignal)10, ctx =>
             {
                 ctx.Cancel = true;
-                _logger.LogWarning("Trapped SIGUSR1 signal — log reopen not yet supported");
+                _logger.LogInformation("Trapped SIGUSR1 signal — reopening log file");
+                ReOpenLogFile?.Invoke();
             }));
 
             _signalRegistrations.Add(PosixSignalRegistration.Create((PosixSignal)12, ctx =>