| Ippei Watanabe | |
| Nationality: | Japanese |
| Strokes: | Breaststroke |
| Birth Date: | 18 March 1997 |
| Birth Place: | Tsukumi, Ōita, Japan |
| Height: | 1.93 m |
| Weight: | 80 kg |
| Show-Medals: | yes |
is a Japanese swimmer and former world record holder in the 200 metre breaststroke.
He competed in the men's 100 metre breaststroke event at the 2016 Summer Olympics.[1] On 9 August 2016, Watanabe broke the Olympic record for the men's 200 metre breaststroke event at the 2016 Summer Olympics during the semi-final. In the final, he finished 6th.
At the Kosuke Kitajima Cup in Tokyo he broke the long course 200 metre breaststroke world record in a time of 2:06.67. He is also the first swimmer ever to go under 2:07.[2]