diff --git a/types/office-js-preview/index.d.ts b/types/office-js-preview/index.d.ts
index a8cb1ae9a91880..c5cc1d050e40d6 100644
--- a/types/office-js-preview/index.d.ts
+++ b/types/office-js-preview/index.d.ts
@@ -7280,6 +7280,14 @@ declare namespace Office {
          * event.
          */
         themeId: ThemeId;
+        /**
+         * Gets the Office host native theme.
+         *
+         * @remarks
+         *
+         * **Important**: The `fluentThemeData` property is only supported on Win32.
+         */
+        fluentThemeData?: object;
     }
     /**
      * Specifies a cell, or row, or column, by its zero-based row and/or column number. Example: `{row: 3, column: 4}` specifies the cell in the 3rd
diff --git a/types/office-js/index.d.ts b/types/office-js/index.d.ts
index 8ad6e2cdc5d2a5..482eefbb305d20 100644
--- a/types/office-js/index.d.ts
+++ b/types/office-js/index.d.ts
@@ -7270,6 +7270,14 @@ declare namespace Office {
          * event.
          */
         themeId: ThemeId;
+        /**
+         * Gets the Office host native theme.
+         *
+         * @remarks
+         *
+         * **Important**: The `fluentThemeData` property is only supported on Win32.
+         */
+        fluentThemeData?: object;
     }
     /**
      * Specifies a cell, or row, or column, by its zero-based row and/or column number. Example: `{row: 3, column: 4}` specifies the cell in the 3rd