diff --git a/.changeset/mime-guess-upload.md b/.changeset/mime-guess-upload.md
new file mode 100644
index 00000000..83a3807d
--- /dev/null
+++ b/.changeset/mime-guess-upload.md
@@ -0,0 +1,5 @@
+---
+"@googleworkspace/cli": patch
+---
+
+Replace hand-rolled MIME type lookup with mime_guess2 crate for upload content-type inference
diff --git a/Cargo.lock b/Cargo.lock
index 0d55ea8d..5735e416 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -226,9 +226,9 @@ dependencies = [
 
 [[package]]
 name = "cc"
-version = "1.2.56"
+version = "1.2.57"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "aebf35691d1bfb0ac386a69bac2fde4dd276fb618cf8bf4f5318fe285e821bb2"
+checksum = "7a0dd1ca384932ff3641c8718a02769f1698e7563dc6974ffd03346116310423"
 dependencies = [
  "find-msvc-tools",
  "shlex",
@@ -904,6 +904,7 @@ dependencies = [
  "hostname",
  "iana-time-zone",
  "keyring",
+ "mime_guess2",
  "percent-encoding",
  "rand 0.8.5",
  "ratatui",
@@ -1477,6 +1478,24 @@ dependencies = [
  "autocfg",
 ]
 
+[[package]]
+name = "mime"
+version = "0.3.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6877bb514081ee2a7ff5ef9de3281f14a4dd4bceac4c09388074a6b5df8a139a"
+
+[[package]]
+name = "mime_guess2"
+version = "2.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1706dc14a2e140dec0a7a07109d9a3d5890b81e85bd6c60b906b249a77adf0ca"
+dependencies = [
+ "mime",
+ "phf 0.11.3",
+ "phf_shared 0.11.3",
+ "unicase",
+]
+
 [[package]]
 name = "minimal-lexical"
 version = "0.2.1"
@@ -1723,6 +1742,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "syn 2.0.117",
+ "unicase",
 ]
 
 [[package]]
@@ -1732,6 +1752,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "67eabc2ef2a60eb7faa00097bd1ffdb5bd28e62bf39990626a582201b7a754e5"
 dependencies = [
  "siphasher",
+ "unicase",
 ]
 
 [[package]]
@@ -2741,9 +2762,9 @@ dependencies = [
 
 [[package]]
 name = "tinyvec"
-version = "1.10.0"
+version = "1.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bfa5fdc3bce6191a1dbc8c02d5c8bffcf557bafa17c124c5264a458f1b0613fa"
+checksum = "3e61e67053d25a4e82c844e8424039d9745781b3fc4f32b8d55ed50f5f667ef3"
 dependencies = [
  "tinyvec_macros",
 ]
@@ -2954,6 +2975,12 @@ version = "0.1.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2896d95c02a80c6d6a5d6e953d479f5ddf2dfdb6a244441010e373ac0fb88971"
 
+[[package]]
+name = "unicase"
+version = "2.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dbc4bc3a9f746d862c45cb89d705aa10f187bb96c76001afab07a0d35ce60142"
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.24"
diff --git a/Cargo.toml b/Cargo.toml
index 24bc253b..0e1f0eda 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -56,6 +56,7 @@ crossterm = "0.29.0"
 chrono = "0.4.44"
 chrono-tz = "0.10"
 iana-time-zone = "0.1"
+mime_guess2 = "2.3"
 async-trait = "0.1.89"
 serde_yaml = "0.9.34"
 percent-encoding = "2.3.2"
diff --git a/src/executor.rs b/src/executor.rs
index 73fd772f..ef7ff6d4 100644
--- a/src/executor.rs
+++ b/src/executor.rs
@@ -808,7 +808,7 @@ fn resolve_upload_mime(
     }
 
     if let Some(path) = upload_path {
-        if let Some(detected) = mime_from_extension(path) {
+        if let Some(detected) = mime_guess2::from_path(path).first() {
             return detected.to_string();
         }
     }
@@ -824,33 +824,6 @@ fn resolve_upload_mime(
     "application/octet-stream".to_string()
 }
 
-/// Infers a MIME type from a file path's extension.
-fn mime_from_extension(path: &str) -> Option<&'static str> {
-    let ext = std::path::Path::new(path)
-        .extension()
-        .and_then(|e| e.to_str())?;
-    match ext.to_lowercase().as_str() {
-        "md" | "markdown" => Some("text/markdown"),
-        "html" | "htm" => Some("text/html"),
-        "txt" => Some("text/plain"),
-        "json" => Some("application/json"),
-        "csv" => Some("text/csv"),
-        "xml" => Some("application/xml"),
-        "pdf" => Some("application/pdf"),
-        "png" => Some("image/png"),
-        "jpg" | "jpeg" => Some("image/jpeg"),
-        "gif" => Some("image/gif"),
-        "svg" => Some("image/svg+xml"),
-        "doc" => Some("application/msword"),
-        "docx" => Some("application/vnd.openxmlformats-officedocument.wordprocessingml.document"),
-        "xls" => Some("application/vnd.ms-excel"),
-        "xlsx" => Some("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"),
-        "ppt" => Some("application/vnd.ms-powerpoint"),
-        "pptx" => Some("application/vnd.openxmlformats-officedocument.presentationml.presentation"),
-        _ => None,
-    }
-}
-
 /// Builds a streaming multipart/related body for media upload requests.
 ///
 /// Instead of reading the entire file into memory, this streams the file in