Custom Redirects will help us to redirect the user from those old URL to the new URL. This post describe the steps to create a Custom Redirect in Blogger. Just follow the steps below.
1. Login to your Blogger account.
2. In your blogs dashboard , GO to Settings > Search Preferences
3. Click on Custom Redirects > Edit
4. Now you will get something like below image
5. Now Add the your posts Old URL to From textfield and add the posts new URL to To textfield.
( Don't add the full URL just add the the red marked part of the URL in the example below )
6. Click Save and Save Changes.
Update: [ Custom Redirect Mobile Version of Blogger URL ]
You also need to add the mobile version of the old URL to the custom redirect. add ?m=1 after the old post URL to get the mobile version.
That's it ! Now navigate to your posts old URL it will automatically redirects to your posts new URL.