Egill was born in Reykjavík, Iceland, and studied filmmaking at Columbia College Hollywood, a Los Angeles based film school. As a cinematographer, he is perhaps best known for his work on The Wire, CSI: Miami (where he was also a co-producer), Dark Blue and numerous television commercials and music videos. In 2008, he directed the Heroes spin-off miniseries Heroes: Destiny.
He has directed episodes of the television series Dark Blue and CSI: Miami, among others. He has directed several installments of The CW action series Nikita, for which he has received high accolades.
Egill is a four-time nominee for the American Society of Cinematographers Outstanding Achievement Awards, and carried home the award in the television category in 2010 for the Dark Blue episode "Venice Kings", which he also directed. Later that year, he became the first Icelander to be admitted into the ASC.