The actor will play Gerhardt, the brother of Dr Whale (David Anders), TVLine reports.
It is unclear if the character - a good-natured military veteran - is also the brother of Whale's Enchanted Forest counterpart Dr Frankenstein.
Collins's past credits include recent roles on 90210, Ringer, 2 Broke Girls and new ABC drama Last Resort.
He will appear in the 12th episode of Once Upon a Time's second season. Collins confirmed his casting on Twitter, writing that he was "looking forward to embracing [his role] with open arms".
Once Upon a Time airs on Sunday nights on ABC in the US and will return to Channel 5 in the UK in early 2013.
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Watch the stars of Once Upon a Time discuss season two with Digital Spy below: