Sewell is the eighth player to committ to the Hawks this season, with Luke Hodge, Sam Mitchell, Grant Birchall, Ryan Schoenmakers, Paul Puopolo and Shane Savage the others to commit.
The 2007 Peter Crimmins Medallist would have been a restricted free agent at the end of this season under the AFL's new Free Agency policy, but has instead committed to the Hawks.
The 28-year-old has played 163 matches for the Hawks, including playing a vital role in the 2008 premiership side.
He was drafted with pick 7 in the 2003 Rookie draft, before being elevated to Hawthorn's senior list in 2004, when he made his senior AFL debut.
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