Competition commissioner Margrethe Vestager is leading the way and says the probe will look into whether the potential acquisition could "distort competition".
The European Union has launched an investigation into Google's plan to acquire fitness tracking device company Fitbit over concerns of additional swathes of data being used for personalised advertising.
European Commission Executive Vice-President Margrethe Vestager, who is also the EU's competition commissioner, said the probe would look into whether a buy-out would not "distort competition" across the online market.
It would also look into whether the acquisition would make it harder for wearable devices developed by rivals to work with Android.
The EU is particularly concerned that an increased "data advantage" for Google could also lead to competitors raising the stakes for online advertising services.
Google agreed to acquire Fitbit in November for $2.1 billion (€1.8 billion) - but the deal was met with criticism from consumer groups highlighting privacy and antitrust concerns.
The tech giant itself has itself tried to alleviate concerns by pledging to submit data gathered under the deal to a virtual data silo, with Rick Osterloh, the company's senior vice president for devices and services, saying the "deal is about devices, not data".
He added in a blog post on the matter: "We’ve been clear from the beginning that we will not use Fitbit health and wellness data for Google ads."
But EU regulators have stressed that this isn't satisfactory enough as the pledge does not cover the entirety of data that could be accessed under the Google-Fitbit deal.
The EU Commission now has until December to make a decision in an investigation seen as the latest move to regulate tech companies.
Vestager has been a particular key player in this stand, having already handed Google nearly $10 billion (€8.5 billion) in fines for numerous antitrust cases during her first five-year term as competition commissioner.