iCloud & iCloud Photos · Messages, Mail and device backups in iCloud
Do WhatsApp chat backups use my iCloud storage?
Short answer: Yes — WhatsApp on iPhone backs chats and media up to iCloud, and it counts toward your storage, growing fast with videos. Exclude videos in WhatsApp's backup settings, and remove old backups from iCloud's Manage list only if you won't need them.
Yes. On iPhone, WhatsApp backs up chats and media to iCloud, and that counts toward your iCloud storage. Videos make it grow quickly.
To shrink it, open WhatsApp's chat backup settings on the iPhone and turn off including videos, or back up less often. Old backups can be removed from the Manage list in iCloud settings — but only if you don't need them to restore chats. See what's using your iCloud storage.