From 2009 to 2010 Hannelius starred as Amy Little in the series Leo Little’s Big Show. From 2009 to 2010 she starred as Dakota Condor in the television series Sonny with a Chance. She is best known for starring as Avery Jennings in the TV series Dog with a Blog since 2012. She has starred in the movies Black & Blue and The Search for Santa Paws and has voiced roles for the films Spooky Buddies, Treasure Buddies, Santa Paws 2: The Santa Pups, and Super Buddies. She has released several albums and songs as a singer and does nail art tutorials on her YouTube channel GbyGNailArt. She has also launched customized nail wrap app called Make Me Nails.