First of all, save your logo as an image. And then you can insert your logo or images into signature with following steps:

1. In the Message window, click the Signature button in the Include group under Message tab.

Apart from the way above, you can also get the Signature button in the Include group under the Insert tab.

2. Click the Signatures item in the drop down list.

3. In the Signature and Stationery dialog box, select one signature that you will add a logo or image to in the Select signature to edit box.

4. In the Edit signature section, place the cursor at the position where you will insert a logo or image.

5. Click the Image button .

6. In the Insert Picture dialog box, select the logo or image you will insert, and click the Insert button. After clicking the Insert button, you can see the logo or image is inserted in the signature.

7. Click the OK button in the Signature and Stationery dialog box.

Note: Up to now you have inserted your logo or image into selected signature. If you set this signature with logo or image as default signature, the inserted logo or image and original signature information will show in every message you compose automatically.

Automatically add text and current datetime/timestamps/timezone to subject or signature in Outlook

Provided by Kutools for Outlook.