Marco De Tullio (born 21 September 2000)[1] is an Italian swimmer.

He represented Italy at the 2019 World Aquatics Championships held in Gwangju, South Korea.

[2] In 2018, he represented Italy at the Summer Youth Olympics in Buenos Aires, Argentina.

[3][4] In the boys' 400 metre freestyle event he won the silver medal and in the boys' 800 metre freestyle event he won the bronze medal.

[3][4] In 2021, he won the bronze medal in the men's 4 × 200 metre freestyle relay event at the 2020 European Aquatics Championships held in Budapest, Hungary.