Google has been fined €4.34bn (£3.8bn) by the EU for abusing its control of the Android operating system by forcing vendors to pre-install its apps.
Announcing the record fine, the EU's competition commissioner Margrethe Vestager said Google was in breach of competition law barring companies from exploiting their market dominance.
"Google must now bring the conduct effectively to an end within 90 days or face penalty payments of up to 5% of the average daily worldwide turnover of Alphabet, Google's parent company," the EU said.
Google plans to appeal against the decision.
"Android has created more choice for everyone, not less. A vibrant ecosystem, rapid innovation, and lower prices are classic hallmarks of robust competition," said a spokesperson for the company.
Google Search is pre-installed as the default web search service on most Android devices sold in Europe, closing off ways for rival search engines to access the market according to the EU ruling.