[1] He appeared in the movie RV as Billy Gornicke,[2] The Invisible as Victor Newton, Diary of a Wimpy Kid as Collin Lee[1][2] and The Time Traveler's Wife as Young Henry DeTamble.
[2][3] He played in the Showtime Network's The L Word as Wilson Mann-Peabody, son of Helena.
He also played Young Sam Winchester in the TV series Supernatural, episode "Something Wicked".
Kennelly in the first four seasons of the television series Martha Speaks, Paulie the Pliosaurus in Dinosaur Train, Dreamfish in the Barbie animated movie Barbie in A Mermaid Tale, and Charlie Brown in Peanuts Motion Comics in 2008.
In 2016, he starred as Astrov in Timothy Koh's production of Uncle Vanya at the 440 Studios Black Box.