diff --git a/lua/sidekick/cli/session/tmux.lua b/lua/sidekick/cli/session/tmux.lua
index 942ed7d1..0d649b8f 100644
--- a/lua/sidekick/cli/session/tmux.lua
+++ b/lua/sidekick/cli/session/tmux.lua
@@ -79,6 +79,9 @@ function M:add_cmd(ret)
       vim.list_extend(ret, { "-e", ("%s=%s"):format(key, tostring(value)) })
     end
   end
+  if Config.cli.mux.direnv and vim.fn.executable("direnv") == 1 then
+    vim.list_extend(ret, { "direnv", "exec", self.cwd })
+  end
   vim.list_extend(ret, self.tool.cmd)
 end
 
diff --git a/lua/sidekick/config.lua b/lua/sidekick/config.lua
index 564617ee..9c65eb0c 100644
--- a/lua/sidekick/config.lua
+++ b/lua/sidekick/config.lua
@@ -94,6 +94,10 @@ local defaults = {
         vertical = true, -- vertical or horizontal split
         size = 0.5, -- size of the split (0-1 for percentage)
       },
+      -- when true and `direnv` is on PATH, tool commands spawned in external
+      -- tmux panes are wrapped with `direnv exec <cwd>` so per-project
+      -- .envrc files are applied.
+      direnv = false,
     },
     --- Actual cli tool config is loaded from the runtime path `sk/cli/{tool}.lua` and merged with the config below.
     --- For default configs, see https://github.com/folke/sidekick.nvim/tree/main/sk/cli