diff --git a/news/357.bugfix.md b/news/357.bugfix.md
new file mode 100644
index 00000000..3efdd799
--- /dev/null
+++ b/news/357.bugfix.md
@@ -0,0 +1 @@
+Fixed subcommand completions for Fish.
diff --git a/src/cleo/commands/completions_command.py b/src/cleo/commands/completions_command.py
index 6a9df744..3c9d422b 100644
--- a/src/cleo/commands/completions_command.py
+++ b/src/cleo/commands/completions_command.py
@@ -249,26 +249,54 @@ def sanitize(s: str) -> str:
         # Commands + options
         cmds = []
         cmds_opts = []
-        cmds_names = []
+        namespaces = set()
         for cmd in sorted(self.application.all().values(), key=lambda c: c.name or ""):
             if cmd.hidden or not cmd.enabled or not cmd.name:
                 continue
-            command_name = shell_quote(cmd.name) if " " in cmd.name else cmd.name
-            cmds.append(
-                f"complete -c {script_name} -f -n '__fish{function}_no_subcommand' "
-                f"-a {command_name} -d '{sanitize(cmd.description)}'"
-            )
+            cmd_path = cmd.name.split(" ")
+            namespace = cmd_path[0]
+            cmd_name = cmd_path[-1] if " " in cmd.name else cmd.name
+
+            # We either have a command like `poetry add` or a nested (namespaced)
+            # command like `poetry cache clear`.
+            if len(cmd_path) == 1:
+                cmds.append(
+                    f"complete -c {script_name} -f -n '__fish{function}_no_subcommand' "
+                    f"-a {cmd_name} -d '{sanitize(cmd.description)}'"
+                )
+                condition = f"__fish_seen_subcommand_from {cmd_name}"
+            else:
+                # Complete the namespace first
+                if namespace not in namespaces:
+                    cmds.append(
+                        f"complete -c {script_name} -f -n "
+                        f"'__fish{function}_no_subcommand' -a {namespace}"
+                    )
+                # Now complete the command
+                subcmds = [
+                    name.split(" ")[-1] for name in self.application.all(namespace)
+                ]
+                cmds.append(
+                    f"complete -c {script_name} -f -n '__fish_seen_subcommand_from "
+                    f"{namespace}; and not __fish_seen_subcommand_from {' '.join(subcmds)}' "  # noqa: E501
+                    f"-a {cmd_name} -d '{sanitize(cmd.description)}'"
+                )
+                condition = (
+                    f"__fish_seen_subcommand_from {namespace}; "
+                    f"and __fish_seen_subcommand_from {cmd_name}"
+                )
+
             cmds_opts += [
-                f"# {command_name}",
+                f"# {cmd.name}",
                 *[
                     f"complete -c {script_name} -A "
-                    f"-n '__fish_seen_subcommand_from {sanitize(command_name)}' "
+                    f"-n '{condition}' "
                     f"-l {opt.name} -d '{sanitize(opt.description)}'"
                     for opt in sorted(cmd.definition.options, key=lambda o: o.name)
                 ],
                 "",  # newline
             ]
-            cmds_names.append(command_name)
+            namespaces.add(namespace)
 
         return TEMPLATES["fish"] % {
             "script_name": script_name,
@@ -276,7 +304,7 @@ def sanitize(s: str) -> str:
             "opts": "\n".join(opts),
             "cmds": "\n".join(cmds),
             "cmds_opts": "\n".join(cmds_opts[:-1]),  # trim trailing newline
-            "cmds_names": " ".join(cmds_names),
+            "cmds_names": " ".join(sorted(namespaces)),
         }
 
     def get_shell_type(self) -> str:
diff --git a/tests/commands/completion/fixtures/fish.txt b/tests/commands/completion/fixtures/fish.txt
index e47611d3..07a991bc 100644
--- a/tests/commands/completion/fixtures/fish.txt
+++ b/tests/commands/completion/fixtures/fish.txt
@@ -1,6 +1,6 @@
 function __fish_my_function_no_subcommand
     for i in (commandline -opc)
-        if contains -- $i command:with:colons hello help list 'spaced command'
+        if contains -- $i command:with:colons hello help list spaced
             return 1
         end
     end
@@ -21,7 +21,8 @@ complete -c script -f -n '__fish_my_function_no_subcommand' -a command:with:colo
 complete -c script -f -n '__fish_my_function_no_subcommand' -a hello -d 'Complete me please.'
 complete -c script -f -n '__fish_my_function_no_subcommand' -a help -d 'Displays help for a command.'
 complete -c script -f -n '__fish_my_function_no_subcommand' -a list -d 'Lists commands.'
-complete -c script -f -n '__fish_my_function_no_subcommand' -a 'spaced command' -d 'Command with space in name.'
+complete -c script -f -n '__fish_my_function_no_subcommand' -a spaced
+complete -c script -f -n '__fish_seen_subcommand_from spaced; and not __fish_seen_subcommand_from command' -a command -d 'Command with space in name.'
 
 # command options
 
@@ -36,5 +37,5 @@ complete -c script -A -n '__fish_seen_subcommand_from hello' -l option-without-d
 
 # list
 
-# 'spaced command'
-complete -c script -A -n '__fish_seen_subcommand_from \'spaced command\'' -l goodbye -d ''
+# spaced command
+complete -c script -A -n '__fish_seen_subcommand_from spaced; and __fish_seen_subcommand_from command' -l goodbye -d ''