Aidan began his acting career in 2013. He is known for starring in Nickelodeon's Nicky, Ricky, Dicky and Dawn as Nicky Harper, for which he was nominated favorite Male TV Star in the Kids Choice Awards in both 2016 and 2017. He is an active advocate for environmental issues and works with a number of environmental organizations, including Waterkeeper Alliance, WildAid, and Oceanic Preservation Society. In 2018, at age 14, Aidan was named as a Goodwill Ambassador for North America, becoming the youngest Goodwill Ambassador.
- Aidan Gallagher named UN Environment Goodwill Ambassador. UN Environment (June 3, 2018). Archived from the original on August 25, 2018. Retrieved on January 17, 2021.