Cheil Worldwide
| Native name | 제일기획 | 
|---|---|
| Company type | Public | 
| KRX: 030000 | |
| Industry | Advertising | 
| Founded | January 17, 1973 | 
| Founder | Lee Byung-chul | 
| Headquarters | , South Korea | 
| Area served | Worldwide | 
| Key people | Kim Jong-hyun (president & CEO) | 
| Owner | Samsung Electronics (28.43%) | 
| Parent | Samsung Group | 
| Subsidiaries | Samsung Sports | 
| Website | Cheil.com/ | 
| Cheil Worldwide | |
| Hangul | 제일기획 | 
|---|---|
| Hanja | 第一企劃 | 
| Revised Romanization | Jeil Gihoek | 
| McCune–Reischauer | Cheil Kihoek | 
Cheil Worldwide Inc. (Korean: 제일기획) is a marketing company under the Samsung Group that offers advertising, public relations, shopper marketing, sports marketing, digital marketing, etc. It was established in 1973 with headquarters in Seoul, South Korea.
It is the country's largest and the world's 10th largest advertising agency, by 2022 revenues, and the world's 14th creative agency network. Its major clients include Samsung, Absolut, Adidas, The Coca-Cola Company, GE, General Motors, The Lego Group, Microsoft, Nestle, and Shell. It has 53 offices spread across 5 continents and CIS.