According to Bloody Disgusting, the child actor will play Carl Grimes, son of protagonist Rick.
Riggs - who turns 11 later this month - has previously appeared in the films Get Low and The Wronged Man. He joins Andrew Lincoln, Sarah Wayne Callies, Jeffrey DeMunn, Jon Bernthal, Laurie Holden and Steven Yeun on the Image Comics-based project.
Directed by Frank Darabont, The Walking Dead has received a six-episode order for its first series.
The show debuts on AMC in October.