Transfer WhatsApp Messages from iPhone to iPhoneNote:
Make sure that iCloud Backup on your iPhone has been turned on. If not, act as below.
Step 1 Back Up WhatsApp Messages on the Old iPhone
Go to "Settings" > "Chat Settings".
Hit "Chat Backup".
Select "Back Up Now".
Ensure that your iCloud have enough space to store the backup. Click Settings > iCloud > Storage to check.
Step 2 Sign in WhatsApp on Another iPhone
Open WhatsApp on another iPhone.
Confirm your country code and enter your phone number.
Tap "Done" at the upper-right corner.
Tap "Yes" on the pop-up.
You will receive an SMS with a code to the number above. Complete your verification by entering the 6-digit activation code.
Step 3 Restore WhatsApp from iCloud Backup
Tap "Restore Chat History".
You will not be able to restore later if you decline to restore now. Restore will take some time.
When restoring completes, go to Chats by following the on-screen prompts. You will see all the restored chats. Tap whichever one of them. You can check the chat history of it.
For Android users, click here and refer to How to Transfer WhatsApp Messages from Android to Android. If you have previously created a backup of your iPhone with iTunes or iCloud, it is available to retrieve your WhatsApp chat history with your backup. Learn more about backing up and restoring your iPhone from the Apple Support page.