Hannes graduated from the acting department of The Icelandic University of the Arts in 2009. Hannes worked at the National Theatre of Iceland 2010-2011 and 2014-2015 (productions include King Lear and All My Sons), at Akureyri Theatre Company 2012-2014 (productions include I Hired A Contract Killer and The Golden Gate) and at Reykjavik City Theatre 2017-2019 (productions include 1984, People Places and Things, and Heaven and Hell). Hannes has worked extensively in various independent theatre and dance productions from 2009 to the present day. Productions include Orphans, I Am the Wind, Shake Me, Whoops!, The Elusive Portal and Evil.
Hannes was nominated for The Icelandic Film Awards as Best Supporting Actor in 2014 for Metalhead and for The Icelandic Theatre Awards as Best Supporting Actor in 2016 for Evil and in 2018 for Heaven and Hell. Film and television credits include the TV series Sense8, Documentary Now! and Stella Blomkvist, and films such as Bjarnfredarson, Metalhead, The County and Eurovision Song Contest: The Story of Fire Saga. Hannes has taught at the theater department at The Icelandic University of the Arts and The Icelandic Film School.