Haskell, who played in Dunedin recently during the Rugby World Cup, will join the team from Japan.
Another newcomer is Chris Noakes, who was let go by Otago last year and has been playing for Bay of Plenty. He provides cover for Colin Slade and Lima Sopoaga.
Otherwise, the squad had been well signposted, with All Blacks Andrew Hore and Hosea Gear coming south from the Hurricanes, one-cap midfield back Tamati Ellison signing on, and newcomers Culum Retallick, Doug Tietjens and Ma'afu Fia joining Jamie Joseph's team.
Highlanders 2012 squad
Fullbacks: Ben Smith, Kurt Baker.
Wingers: Hosea Gear, Kade Poki, Siale Piutau, Telusa Veainu.
Midfielders: Shaun Treeby, Kendrick Lynn, Tamati Ellison.
First fives: Colin Slade, Lima Sopoaga, Chris Noakes.
Halfbacks: Jimmy Cowan, Aaron Smith.
Loose forwards: Adam Thomson, James Haskell, Nasi Manu, John Hardie, Nick Crosswell, Elliot Dixon, Doug Tietjens.
Locks: Josh Bekhuis, Jarrad Hoeata, Culum Retallick.
Props: Jamie Mackintosh, Chris King, Bronson Murray, Ma'afu Fia.
Hookers: Andrew Hore, Jason Rutledge.