She is also well-known for voice acting work on other 4Kids anime, including Pokémon and Sonic X up until her departure from the company. She has also voiced in various Viz Media and Bandai Entertainment anime, including Bleach and Eureka Seven. Some of her work is done under the pseudonym Karen Thompson.
Hollingshead's major role on the anime was portraying Mai Valentine from Episode 3 to Episode 144. This role was taken over by Bella Hudson in season 4 onwards following Hollingshead's departure from 4Kids. Other roles include the synthetic voice of Seto Kaiba's computer from Episode 9, 10, 143 and Cecelia Pegasus.
- Since her departure from the series, she, along with fellow former Yu-Gi-Oh! voice actress Tara Sands, worked together on Tales of Symphonia: Dawn of the New World as Sheena Fujibayashi and Genis Sage respectfully, though neither of them were credited for it.