The 19 companies include Alphabet's Google Maps, Google Play, Google Search, Google Shopping and YouTube, Meta's Facebook and Instagram, Amazon's (AMZN.O) Marketplace and Apple's App Store.
The others are Microsoft's two units Linkedin and Bing, booking.com (BKNG.O), Pinterest (PINS.N), Snap Inc's (SNAP.N) Snapchat, TikTok, Twitter, Wikipedia, Zalando (ZALG.DE) and Alibaba's (9988.HK) AliExpress.
"We consider these 19 online platforms and search engines have become systematically relevant and have special responsibilities to make the internet safer," Breton told reporters.
Breton singled out Facebook's content moderation system for criticism because of its role in building opinions on key issues.
So I look forward to an invitation to Bytedance's headquarters to understand better the origin of Tiktok," Breton said.