diff --git a/src/client/commands/create_db.rs b/src/client/commands/create_db.rs
index b59ee26..cd08c7c 100644
--- a/src/client/commands/create_db.rs
+++ b/src/client/commands/create_db.rs
@@ -1,10 +1,12 @@
 use clap::Parser;
+use clap_complete::ArgValueCompleter;
 use futures_util::SinkExt;
 use tokio_stream::StreamExt;
 
 use crate::{
     client::commands::{erroneous_server_response, print_authorization_owner_hint},
     core::{
+        completion::prefix_completer,
         protocol::{
             ClientToServerMessageStream, CreateDatabaseError, Request, Response,
             print_create_databases_output_status, print_create_databases_output_status_json,
@@ -18,6 +20,7 @@ use crate::{
 pub struct CreateDbArgs {
     /// The MySQL database(s) to create
     #[arg(num_args = 1.., value_name = "DB_NAME")]
+    #[cfg_attr(not(feature = "suid-sgid-mode"), arg(add = ArgValueCompleter::new(prefix_completer)))]
     name: Vec<MySQLDatabase>,
 
     /// Print the information as JSON
diff --git a/src/client/commands/create_user.rs b/src/client/commands/create_user.rs
index 26cd14c..72a4340 100644
--- a/src/client/commands/create_user.rs
+++ b/src/client/commands/create_user.rs
@@ -1,4 +1,5 @@
 use clap::Parser;
+use clap_complete::ArgValueCompleter;
 use dialoguer::Confirm;
 use futures_util::SinkExt;
 use tokio_stream::StreamExt;
@@ -9,6 +10,7 @@ use crate::{
         read_password_from_stdin_with_double_check,
     },
     core::{
+        completion::prefix_completer,
         protocol::{
             ClientToServerMessageStream, CreateUserError, Request, Response,
             print_create_users_output_status, print_create_users_output_status_json,
@@ -22,6 +24,7 @@ use crate::{
 pub struct CreateUserArgs {
     /// The MySQL user(s) to create
     #[arg(num_args = 1.., value_name = "USER_NAME")]
+    #[cfg_attr(not(feature = "suid-sgid-mode"), arg(add = ArgValueCompleter::new(prefix_completer)))]
     username: Vec<MySQLUser>,
 
     /// Do not ask for a password, leave it unset
diff --git a/src/client/mysql_admutils_compatibility/mysql_dbadm.rs b/src/client/mysql_admutils_compatibility/mysql_dbadm.rs
index 9de318e..d37e485 100644
--- a/src/client/mysql_admutils_compatibility/mysql_dbadm.rs
+++ b/src/client/mysql_admutils_compatibility/mysql_dbadm.rs
@@ -18,7 +18,7 @@ use crate::{
     },
     core::{
         bootstrap::bootstrap_server_connection_and_drop_privileges,
-        completion::mysql_database_completer,
+        completion::{mysql_database_completer, prefix_completer},
         database_privileges::DatabasePrivilegeRow,
         protocol::{
             ClientToServerMessageStream, ListPrivilegesError, Request, Response,
@@ -124,6 +124,7 @@ pub enum Command {
 pub struct CreateArgs {
     /// The name of the DATABASE(s) to create.
     #[arg(num_args = 1..)]
+    #[cfg_attr(not(feature = "suid-sgid-mode"), arg(add = ArgValueCompleter::new(prefix_completer)))]
     name: Vec<MySQLDatabase>,
 }
 
diff --git a/src/client/mysql_admutils_compatibility/mysql_useradm.rs b/src/client/mysql_admutils_compatibility/mysql_useradm.rs
index c0fa4bf..d61f52c 100644
--- a/src/client/mysql_admutils_compatibility/mysql_useradm.rs
+++ b/src/client/mysql_admutils_compatibility/mysql_useradm.rs
@@ -18,7 +18,7 @@ use crate::{
     },
     core::{
         bootstrap::bootstrap_server_connection_and_drop_privileges,
-        completion::mysql_user_completer,
+        completion::{mysql_user_completer, prefix_completer},
         protocol::{
             ClientToServerMessageStream, Request, Response, create_client_to_server_message_stream,
         },
@@ -87,6 +87,7 @@ pub enum Command {
 pub struct CreateArgs {
     /// The name of the USER(s) to create.
     #[arg(num_args = 1..)]
+    #[cfg_attr(not(feature = "suid-sgid-mode"), arg(add = ArgValueCompleter::new(prefix_completer)))]
     name: Vec<MySQLUser>,
 }
 
diff --git a/src/core/completion.rs b/src/core/completion.rs
index 2e68e28..d4dead0 100644
--- a/src/core/completion.rs
+++ b/src/core/completion.rs
@@ -1,5 +1,7 @@
 mod mysql_database_completer;
 mod mysql_user_completer;
+mod prefix_completer;
 
 pub use mysql_database_completer::*;
 pub use mysql_user_completer::*;
+pub use prefix_completer::*;
diff --git a/src/core/completion/prefix_completer.rs b/src/core/completion/prefix_completer.rs
new file mode 100644
index 0000000..5eee537
--- /dev/null
+++ b/src/core/completion/prefix_completer.rs
@@ -0,0 +1,75 @@
+use clap_complete::CompletionCandidate;
+use clap_verbosity_flag::Verbosity;
+use futures_util::SinkExt;
+use tokio::net::UnixStream as TokioUnixStream;
+use tokio_stream::StreamExt;
+
+use crate::{
+    client::commands::erroneous_server_response,
+    core::{
+        bootstrap::bootstrap_server_connection_and_drop_privileges,
+        protocol::{Request, Response, create_client_to_server_message_stream},
+    },
+};
+
+pub fn prefix_completer(current: &std::ffi::OsStr) -> Vec<CompletionCandidate> {
+    match tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+    {
+        Ok(runtime) => match runtime.block_on(prefix_completer_(current)) {
+            Ok(completions) => completions,
+            Err(err) => {
+                eprintln!("Error getting prefix completions: {}", err);
+                Vec::new()
+            }
+        },
+        Err(err) => {
+            eprintln!("Error starting Tokio runtime: {}", err);
+            Vec::new()
+        }
+    }
+}
+
+/// Connect to the server to get MySQL user completions.
+async fn prefix_completer_(_current: &std::ffi::OsStr) -> anyhow::Result<Vec<CompletionCandidate>> {
+    let server_connection =
+        bootstrap_server_connection_and_drop_privileges(None, None, Verbosity::new(0, 1))?;
+
+    let tokio_socket = TokioUnixStream::from_std(server_connection)?;
+    let mut server_connection = create_client_to_server_message_stream(tokio_socket);
+
+    while let Some(Ok(message)) = server_connection.next().await {
+        match message {
+            Response::Error(err) => {
+                anyhow::bail!("{}", err);
+            }
+            Response::Ready => break,
+            message => {
+                eprintln!("Unexpected message from server: {:?}", message);
+            }
+        }
+    }
+
+    let message = Request::ListValidNamePrefixes;
+
+    if let Err(err) = server_connection.send(message).await {
+        server_connection.close().await.ok();
+        anyhow::bail!(anyhow::Error::from(err).context("Failed to communicate with server"));
+    }
+
+    let result = match server_connection.next().await {
+        Some(Ok(Response::ListValidNamePrefixes(prefixes))) => prefixes,
+        response => return erroneous_server_response(response).map(|_| vec![]),
+    };
+
+    server_connection.send(Request::Exit).await?;
+
+    let result = result
+        .into_iter()
+        .map(|prefix| prefix + "_")
+        .map(CompletionCandidate::new)
+        .collect();
+
+    Ok(result)
+}