The messaging service currently requires users to be at least 13, but from May 25 and with the introduction of the new General Data Protection Regulation (GDPR), it will increase for those inside the EU.
The Facebook-owned service will ask users to confirm their age when prompting them to agree to new terms of service on the platform in the coming weeks.
WhatsApp said it was not asking for any new rights to collect personal information as part of the new terms.
"Our goal is simply to explain how we use and protect the limited information we have about you," the company said.
Fellow internet giants such as Facebook and Twitter have also been rolling out new terms of service ahead of the GDPR launch, in order to bring their businesses in line with the new regulations - which require clear consent from users to access their data.
The regulations also give users greater powers to access and control how their data is used, and the right to have personal data erased.
WhatsApp said the update ensured it could "meet the new high standards of transparency for how we protect the privacy of our users".
The company said it plans to keep the over-13 age restriction in the rest of the world.
It also confirmed it will launch a feature in the coming weeks that will enable users to download a copy of the data WhatsApp has collected on them - another requirement of GDPR.