Alongside being a child actor, he's also a child voice actor. Aside from We Bare Bears, Duncan has also voiced as a character named Ian in Disney Jr.'s series Doc McStuffins.
- The only two animated series Duncan has been credited for voicing in are We Bare Bears and Doc McStuffins.
- Duncan only voiced Ian in one episode of Doc McStuffins, while all other times the character was voiced by someone else.
|Voice actors||Bobby Moynihan • Charlyne Yi • Demetri Martin • Duncan Joiner • Edi Patterson • Eric Edelstein • Estelle • Jason Lee • Keith Ferguson • Niki Yang • Patton Oswalt • Rodger Bumpass • Sam Lavagnino|
|Show staff||Abe Audish • Brad Breeck • Brian A. Miller • Bert Youn • Christina Chang • Curtis Lelash • Daniel Chong • Danny Ducker • Guillermo Martinez • Jennifer Pelphrey • Kyler Spears • Lauren Sassen • Lilit Atshemyan • Louie Zong • Madeline Sharafian • Manny Hernandez • McKenna Harris • Mikey Heller • Nate Funaro • Nooree Kim • Randy Myers • Rob Sorcher • Sarah Sobole • Teresa Hsiao • Tom Law • Violet Bruce|
|Guests||Adam Campbell • Dia Frampton • Ellie Kemper • Eric Favela • Suzie Vlček • Phil Rynda • Sue Mondt • Vera Brosgol|