Frankie Jonas began his career as a voice actor in 2009 when he was cast as the lead character Sōsuke in the English-language dub of the Hayao Miyazaki animated film Ponyo. At the age of seven, he provided the voice for the young boy who befriends a goldfish princess, starring opposite Noah Cyrus in the title role. Jonas and Cyrus also performed the English version of the film's theme song together.

Following his debut in Ponyo, Jonas took on additional voice acting roles in several films. He voiced the character Pip in the 2011 direct-to-video family film Spooky Buddies. The following year, he provided the voice for Junior in the animated comedy The Reef 2: High Tide. These roles represent the extent of his verified work in voice acting.

Concurrent with his early voice acting career, Jonas appeared in live-action television and film projects, many of which involved his older brothers, the Jonas Brothers. He had a recurring role as Frankie Lucas on the Disney Channel series Jonas from 2009 to 2010. For this performance, he won the Teen Choice Award for Choice TV Breakout Star Male in 2009. He also appeared in the Disney Channel film Camp Rock 2: The Final Jam. In the 2020s, his professional focus shifted primarily to music and television hosting, notably co-hosting the ABC reality competition series Claim to Fame with his brother Kevin beginning in 2022.