diff --git a/xtask/src/cli/mod.rs b/xtask/src/cli/mod.rs
index a074082b08..51fb9b2d65 100644
--- a/xtask/src/cli/mod.rs
+++ b/xtask/src/cli/mod.rs
@@ -15,6 +15,8 @@ pub(crate) struct Cli {
 pub(crate) enum Commands {
     #[command(about = "Run cargo fmt on extendr")]
     CheckFmt,
+    #[command(about = "Run `cargo fmt` on extendr crates")]
+    Fmt,
     #[command(about = "Run R CMD check on {extendrtests}")]
     RCmdCheck(RCmdCheckArg),
     #[command(about = "Generate documentation for all features")]
diff --git a/xtask/src/commands/cargo_fmt.rs b/xtask/src/commands/cargo_fmt.rs
new file mode 100644
index 0000000000..4a499a153a
--- /dev/null
+++ b/xtask/src/commands/cargo_fmt.rs
@@ -0,0 +1,14 @@
+use xshell::{cmd, Error, Shell};
+
+pub(crate) fn run(shell: &Shell) -> Result<(), Error> {
+    // extendr-api, extendr-macros, extendr-engine, xtask
+    cmd!(shell, "cargo fmt --all").run()?;
+    // extendrtests
+    cmd!(
+        shell,
+        "cargo fmt --all --manifest-path tests/extendrtests/src/rust/Cargo.toml"
+    )
+    .run()?;
+
+    Ok(())
+}
diff --git a/xtask/src/commands/cargo_fmt_check.rs b/xtask/src/commands/cargo_fmt_check.rs
index ca0df58fd6..ebcbd0714e 100644
--- a/xtask/src/commands/cargo_fmt_check.rs
+++ b/xtask/src/commands/cargo_fmt_check.rs
@@ -1,12 +1,19 @@
 use xshell::{cmd, Error, Shell};
 
 pub(crate) fn run(shell: &Shell) -> Result<(), Error> {
-    let check_result = cmd!(shell, "cargo fmt -- --check").run();
-    if check_result.is_err() {
-        println!("Please run `cargo fmt --all`");
+    let check_extendr = cmd!(shell, "cargo fmt --all -- --check").run();
+
+    let check_extendrtests = cmd!(
+        shell,
+        "cargo fmt --all --manifest-path tests/extendrtests/src/rust/Cargo.toml -- --check"
+    )
+    .run();
+
+    if check_extendr.is_err() || check_extendrtests.is_err() {
+        println!("Please run `cargo extendr fmt`");
     } else {
         println!("Success!");
     }
 
-    check_result
+    check_extendr
 }
diff --git a/xtask/src/commands/mod.rs b/xtask/src/commands/mod.rs
index 1c20dbbe61..39c8cde597 100644
--- a/xtask/src/commands/mod.rs
+++ b/xtask/src/commands/mod.rs
@@ -1,3 +1,4 @@
+pub(crate) mod cargo_fmt;
 pub(crate) mod cargo_fmt_check;
 pub(crate) mod cargo_msrv;
 pub(crate) mod devtools_test;
diff --git a/xtask/src/main.rs b/xtask/src/main.rs
index a8a1462786..a2a830e593 100644
--- a/xtask/src/main.rs
+++ b/xtask/src/main.rs
@@ -21,6 +21,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
             .canonicalize()?,
     );
     match cli.command {
+        cli::Commands::Fmt => commands::cargo_fmt::run(&shell)?,
         cli::Commands::CheckFmt => commands::cargo_fmt_check::run(&shell)?,
         cli::Commands::RCmdCheck(RCmdCheckArg {
             no_build_vignettes,