diff --git a/.changeset/fix-append-json-multirow.md b/.changeset/fix-append-json-multirow.md
new file mode 100644
index 00000000..1e3f6de0
--- /dev/null
+++ b/.changeset/fix-append-json-multirow.md
@@ -0,0 +1,5 @@
+---
+"@googleworkspace/cli": patch
+---
+
+Fix `+append --json-values` multi-row bug by changing AppendConfig.values to Vec<Vec<String>>
diff --git a/src/helpers/sheets.rs b/src/helpers/sheets.rs
index 5c2a9e90..b179c75c 100644
--- a/src/helpers/sheets.rs
+++ b/src/helpers/sheets.rs
@@ -102,7 +102,7 @@ TIPS:
     ) -> Pin<Box<dyn Future<Output = Result<bool, GwsError>> + Send + 'a>> {
         Box::pin(async move {
             if let Some(matches) = matches.subcommand_matches("+append") {
-                let config = parse_append_args(matches);
+                let config = parse_append_args(matches)?;
                 let (params_str, body_str, scopes) = build_append_request(&config, doc)?;
 
                 let scope_strs: Vec<&str> = scopes.iter().map(|s| s.as_str()).collect();
@@ -222,7 +222,7 @@ fn build_append_request(
     // This allows us to easily create nested objects without defining explicit structs
     // for every API request body.
     let body = json!({
-        "values": [config.values]
+        "values": config.values
     });
 
     // Map `&String` scope URLs to owned `String`s for the return value
@@ -260,35 +260,41 @@ fn build_read_request(
 /// Configuration for appending values to a spreadsheet.
 ///
 /// Holds the parsed arguments for the `+append` subcommand.
+#[derive(Debug)]
 pub struct AppendConfig {
     /// The ID of the spreadsheet to append to.
     pub spreadsheet_id: String,
-    /// The values to append, as a vector of strings.
-    pub values: Vec<String>,
+    /// The values to append, as a 2D array of strings (one inner vec per row).
+    pub values: Vec<Vec<String>>,
 }
 
 /// Parses arguments for the `+append` command.
 ///
 /// Splits the comma-separated `values` argument into a `Vec<String>`.
-pub fn parse_append_args(matches: &ArgMatches) -> AppendConfig {
+pub fn parse_append_args(matches: &ArgMatches) -> Result<AppendConfig, GwsError> {
     let values = if let Some(json_str) = matches.get_one::<String>("json-values") {
-        // Parse JSON array of rows
+        // Try parsing as 2D array first, then fall back to 1D array
         if let Ok(parsed) = serde_json::from_str::<Vec<Vec<String>>>(json_str) {
-            parsed.into_iter().flatten().collect()
+            parsed
         } else {
-            // Treat as single row JSON array
-            serde_json::from_str::<Vec<String>>(json_str).unwrap_or_default()
+            serde_json::from_str::<Vec<String>>(json_str)
+                .map(|row| vec![row])
+                .map_err(|e| {
+                    GwsError::Validation(format!(
+                        "Invalid --json-values: {e}. Expected a JSON array of strings or array of arrays."
+                    ))
+                })?
         }
     } else if let Some(values_str) = matches.get_one::<String>("values") {
-        values_str.split(',').map(|s| s.to_string()).collect()
+        vec![values_str.split(',').map(|s| s.to_string()).collect()]
     } else {
         Vec::new()
     };
 
-    AppendConfig {
+    Ok(AppendConfig {
         spreadsheet_id: matches.get_one::<String>("spreadsheet").unwrap().clone(),
         values,
-    }
+    })
 }
 
 /// Configuration for reading values from a spreadsheet.
@@ -365,14 +371,18 @@ mod tests {
         let doc = make_mock_doc();
         let config = AppendConfig {
             spreadsheet_id: "123".to_string(),
-            values: vec!["a".to_string(), "b".to_string(), "c".to_string()],
+            values: vec![vec!["a".to_string(), "b".to_string(), "c".to_string()]],
         };
         let (params, body, scopes) = build_append_request(&config, &doc).unwrap();
 
         assert!(params.contains("123"));
         assert!(params.contains("USER_ENTERED"));
-        assert!(body.contains("a"));
-        assert!(body.contains("b"));
+
+        let body_json: serde_json::Value = serde_json::from_str(&body).unwrap();
+        assert_eq!(
+            body_json,
+            serde_json::json!({"values": [["a", "b", "c"]]})
+        );
         assert_eq!(scopes[0], "https://scope");
     }
 
@@ -393,9 +403,41 @@ mod tests {
     #[test]
     fn test_parse_append_args() {
         let matches = make_matches_append(&["test", "--spreadsheet", "123", "--values", "a,b,c"]);
-        let config = parse_append_args(&matches);
+        let config = parse_append_args(&matches).unwrap();
         assert_eq!(config.spreadsheet_id, "123");
-        assert_eq!(config.values, vec!["a", "b", "c"]);
+        assert_eq!(config.values, vec![vec!["a", "b", "c"]]);
+    }
+
+    #[test]
+    fn test_parse_append_args_json_multirow() {
+        let matches = make_matches_append(&[
+            "test",
+            "--spreadsheet",
+            "123",
+            "--json-values",
+            r#"[["Alice","100"],["Bob","200"]]"#,
+        ]);
+        let config = parse_append_args(&matches).unwrap();
+        assert_eq!(config.spreadsheet_id, "123");
+        assert_eq!(
+            config.values,
+            vec![vec!["Alice", "100"], vec!["Bob", "200"]]
+        );
+    }
+
+    #[test]
+    fn test_parse_append_args_json_malformed() {
+        let matches = make_matches_append(&[
+            "test",
+            "--spreadsheet",
+            "123",
+            "--json-values",
+            "not valid json",
+        ]);
+        let result = parse_append_args(&matches);
+        assert!(result.is_err());
+        let err_msg = result.unwrap_err().to_string();
+        assert!(err_msg.contains("Invalid --json-values"));
     }
 
     #[test]