Tomkinson will start at centre for the Highlanders on Saturday night against the Chiefs, replacing Michael Collins.
Six players were dropped from last weekend's game after failing to meet team standards.
Josh Ioane, another one of the dirty half dozen, has been named on the bench.
Other changes are made in the front row and James Lentjes gets a start.
Scott Gregory plays in the midfield after a fine showing on the wing last week in the big win over the Crusaders.
Highlanders: Connor Garden-Bachop, Ngatungane Punivai, Sio Tomkinson, Scott Gregory, Jona Nareki, Mitch Hunt, Aaron Smith (co-captain), Kazuki Himeno, James Lentjes, Shannon Frizell, Pari Pari Parkinson, Bryn Evans, Josh Hohneck, Ash Dixon (co-captain), Ethan De Groot.
Reserves: Liam Coltman, Ayden Johnstone, Siate Tokolahi, Josh Dickson, Billy Harmon, Kayne Hammington, Josh Ioane, Hugh Renton
