Ireland's Data Protection Commission (DPC) launched an inquiry into Google Ireland six years ago after complaints from multiple European consumer rights organisations.
The DPC examined the lawfulness and fairness of its processing of location data and Google's accountability obligations under General Data Protection Regulation.
The inquiry found Google users could have been unaware that their location was being used to influence them with ads or to infer their interests.
The inquiry looked at "web and app activity", "location history" and "location accuracy" between May 25, 2018 and February 4, 2020.
The DPC ordered Google to bring its processing into compliance within six months.
It is the fourth largest fine issued by the DPC since the GDPR came into effect.
Deputy commissioner Graham Doyle said: "Location data is a type of personal data which is processed by way of location tracking, and includes data collected or processed by Google, which by itself or in conjunction with other information an individual's location can be inferred.
"Location data can bring both benefits and harms to individuals.
"It can greatly enhance the utility of online services, but it can also reveal a significant amount of information about an individual, including information that is inherently private.
He added: "As a result of Google's failures in this regard, individuals could have been unaware that their location was being used to, for example, influence them with ads or to infer their interests, and could lose control over their personal data.
"The retention of users' location data for longer than necessary aggravated this loss of control."
There are three other ongoing statutory large-scale inquiries open that concern Google, all of which are at an advanced stage.
with PA
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