Coltman (22) won the award after a fine season in which he made an impact playing either hooker or tighthead prop.
His outstanding season won him a place in next year's Highlanders squad.
Initially, Coltman's representative season seemed in doubt after he damaged his neck in a pre-season game, but with a few months' rest he managed to get back on the field and made great progress.
Japanese halfback Fumiaki Tanaka was awarded the David Latta Trophy for his performance this season.
The award, for best contribution by a player both on and off the field, is voted for by the players.
Tanaka (27) had an outstanding season for an Otago side that made it through to the championship final, where it lost to Counties-Manukau.
First five-eighth Hayden Parker was named back of the year, and captain and No8 Paul Grant was forward of the year.
Fullback Tony Ensor was named rookie of the year.
All of the awards, except for Tanaka's, were picked by the coaching staff.
