On the CW drama, Teen Wolf star Haynes will play Roy Harper - the teen character who became the costumed sidekick of Oliver Queen (Stephen Amell) in the original DC comics.
"Our interpretation of Roy is hopefully unexpected," Guggenheim told TV Guide. "Roy is from the Glades, which is part of Starling City that is the slum of the slums."
The streetwise Harper will become romantically involved with Oliver Queen's sister Thea (Willa Holland) in future episodes of the superhero series.
"Obviously he's from a very different side of the tracks from Thea," said Guggenheim. "So that gives us a fun dynamic to play around with. We're designing it to be a longer-term relationship."
Fringe actor Seth Gabel and Spartacus star Manu Bennett will also play guest roles on Arrow later in 2013.
The series returns to The CW in the US on January 16 and is back on Sky1 in the UK on January 21.
> Arrow exec on cult casting: 'We're fans of Torchwood, Farscape'
> Arrow exec confirms Huntress return: 'She's like Oliver's crazy ex'
Watch a promo for the return of Arrow below: