Toby Longworth, an established voice performer for Black Library audiobooks and Warhammer 40k media, was interviewed by PC Gamer about his work on Dawn of War 4. He has previously portrayed numerous Space Marine characters and Primarchs throughout his career with the franchise, bringing vocal performances to recognised figures across both books and video games.

Longworth highlighted a recurring technical hurdle in voicing Space Marines: because they are genetically identical clones within the fiction, they naturally share baseline similarities that make vocal differentiation challenging. To solve this, he employs varied techniques such as altering pitch registers—he cited giving Nathaniel Garro a slightly elevated tone as an example—to ensure listeners can track individual characters during scenes involving multiple Space Marines with similar names and gravelly voices.