Exhibit 99.1 Yatsen Announces Third Quarter 2023 Financial Results and Upsizing and Extension of Share Repurchase Program Conference Call to Be Held at 7:30 A.M. U.S. Eastern Time on November 21, 2023 GUANGZHOU, China, November 21, 2023 – Yatsen Holding Limited ("Yatsen" or the "Company") (NYSE: YSG), a leading China-based beauty group, today announced its unaudited financial results for the third quarter ended September 30, 2023, and upsizing and extension of the share repurchase program. Third Quarter 202 ...