diff --git a/crates/uv-distribution/src/metadata/lowering.rs b/crates/uv-distribution/src/metadata/lowering.rs
index 4cbc12b95b78a..1401cb09fd82c 100644
--- a/crates/uv-distribution/src/metadata/lowering.rs
+++ b/crates/uv-distribution/src/metadata/lowering.rs
@@ -56,6 +56,34 @@ impl LoweredRequirement {
             (None, RequirementOrigin::Project)
         };
 
+        // If the project declares a non-workspace source for a workspace member (e.g., a Git
+        // source for standalone use), but the workspace root declares it as a workspace source,
+        // prefer the workspace root's source.
+        let (sources, origin) = if matches!(origin, RequirementOrigin::Project)
+            && workspace.packages().contains_key(&requirement.name)
+            && sources.is_some_and(|s| s.iter().any(|s| !matches!(s, Source::Workspace { .. })))
+        {
+            if let Some(workspace_source) = workspace.sources().get(&requirement.name) {
+                if workspace_source.iter().any(|s| {
+                    matches!(
+                        s,
+                        Source::Workspace {
+                            workspace: true,
+                            ..
+                        }
+                    )
+                }) {
+                    (Some(workspace_source), RequirementOrigin::Workspace)
+                } else {
+                    (sources, origin)
+                }
+            } else {
+                (sources, origin)
+            }
+        } else {
+            (sources, origin)
+        };
+
         // If the source only applies to a given extra or dependency group, filter it out.
         let sources = sources.map(|sources| {
             sources
diff --git a/crates/uv/tests/it/lock.rs b/crates/uv/tests/it/lock.rs
index 3f9002609e6b5..a4408335974b2 100644
--- a/crates/uv/tests/it/lock.rs
+++ b/crates/uv/tests/it/lock.rs
@@ -9726,6 +9726,86 @@ fn lock_no_workspace_source() -> Result<()> {
     Ok(())
 }
 
+/// When a workspace member declares a non-workspace source (e.g., Git, path) for another workspace
+/// member, but the workspace root declares `workspace = true` for that same member, the workspace
+/// root's source should take precedence. This supports the pattern where members declare
+/// non-workspace sources (e.g., Git, path) for standalone use, while the workspace root overrides
+/// them as workspace sources.
+///
+/// See: <https://github.com/astral-sh/uv/issues/18232>
+#[test]
+fn lock_member_non_workspace_source_with_root_workspace_source() -> Result<()> {
+    let context = uv_test::test_context!("3.12");
+
+    let root_pyproject = context.temp_dir.child("pyproject.toml");
+    root_pyproject.write_str(
+        r#"
+        [project]
+        name = "monorepo"
+        version = "1.0.0"
+        requires-python = ">=3.12"
+        dependencies = ["app-a", "lib-x"]
+
+        [tool.uv.sources]
+        app-a = { workspace = true }
+        lib-x = { workspace = true }
+
+        [tool.uv.workspace]
+        members = ["packages/app-a", "packages/lib-x"]
+        "#,
+    )?;
+
+    let app_a = context.temp_dir.child("packages").child("app-a");
+    fs_err::create_dir_all(&app_a)?;
+
+    let app_a_pyproject = app_a.child("pyproject.toml");
+    app_a_pyproject.write_str(
+        r#"
+        [project]
+        name = "app-a"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = ["lib-x"]
+
+        [tool.uv.sources]
+        lib-x = { path = "../../packages/lib-x", editable = false }
+
+        [build-system]
+        requires = ["uv_build>=0.7,<10000"]
+        build-backend = "uv_build"
+        "#,
+    )?;
+
+    let lib_x = context.temp_dir.child("packages").child("lib-x");
+    fs_err::create_dir_all(&lib_x)?;
+
+    let lib_x_pyproject = lib_x.child("pyproject.toml");
+    lib_x_pyproject.write_str(
+        r#"
+        [project]
+        name = "lib-x"
+        version = "1.0.0"
+        requires-python = ">=3.12"
+        dependencies = []
+
+        [build-system]
+        requires = ["uv_build>=0.7,<10000"]
+        build-backend = "uv_build"
+        "#,
+    )?;
+
+    uv_snapshot!(context.filters(), context.lock(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 3 packages in [TIME]
+    ");
+
+    Ok(())
+}
+
 /// Lock a workspace with a member that's a peer to the root.
 #[test]
 fn lock_peer_member() -> Result<()> {