| David Johnston | |
| Nationality: | American |
| Birth Date: | 28 October 2001[1] |
| Sport: | Men's swimming |
| Strokes: | Freestyle |
| Club: | The Swim Team, Lake Forest, CA |
David Johnston is an American swimmer and 2024 World Aquatics Championships team member for the United States. Johnston qualified for the 400m freestyle and 400m individual Medley.[2] He placed third in the 400m freestyle at the 2024 US Olympic Team Trials.