Eric Loomis was born on October 4, 1964, in Los Angeles County, California. Before establishing himself in animation voiceover, Loomis worked extensively in television and radio commercials for over fifteen years. His clients included major brands such as McDonalds, Carl's Jr., HP, OnStar, Toyota, and Panda Express. One of his most notable achievements in commercial work was providing the campaign voice of Johnny for the Coca Cola product Surge, which received a nomination for a Clio Award in 1998.

Loomis entered the animation field with relatively small roles early in his career. He appeared in the Klasky-Csupo series As Told by Ginger as the voice of Mr. Gardner. He also contributed voice work to the CD-ROM game Star Wars: Rebellion for Lucas Arts, as well as Detective Barbie, and Kureyon Shin-chan.

In the English dub of the anime series Shin Chan produced by Vitello Productions, Loomis performed the roles of both Harry Nohara, who is the father of the title character, and Bo, one of Shin Chan's friends. This production represents his most direct and sustained work within the anime genre.

The most significant turning point in Loomis's voice acting career occurred in 2008 when he was cast as the voice of Tony Stark and his superhero alter ego Iron Man for the Marvel animated series The Avengers: Earth's Mightiest Heroes, which premiered on Disney XD in 2010. This role became a signature part of his career, leading to him voicing the character across multiple other media. He reprised the role of Iron Man in video games including Iron Man 2, Command and Conquer 4: Tiberian Twilight, Marvel vs. Capcom 3: Fate of Two Worlds, Marvel vs. Capcom: Infinite, Marvel Ultimate Alliance 3: The Black Order, and Marvel Future Revolution. He also provided the character's voice for the Marvel Super Heroes 4D attraction. Additionally, Loomis had the opportunity to perform automated dialogue replacement, or ADR, for actor Robert Downey Jr. on several film projects.

Beyond his work in anime and superhero animation, Loomis voiced additional characters in the video game Lightning Returns: Final Fantasy XIII and the role of Po in Kung Fu Panda: Legendary Warriors. He also provided the voice of Snake Oiler for Mattel Toys' Speed Racer product line.