Santner made his international debut on English soil and impressed with his left arm-spin and lower-order batting in the limited-over series.
The 23-year-old, viewed as a potential successor to the retired Daniel Vettori, has been singled out for his bowling but coach Mike Hesson said he expected his talents with the bat to become more prevalent over the next 12 months.
Veteran all-rounder Grant Elliott has also been rewarded with a contract after continuing his fine form from the World Cup into the England tour.
Speaking about Santner, Hesson said: “Mitch is a player of genuine all-round ability. His appearance on this list is recognition of where we see his skills in all three forms of the game.
“My feeling is that we’ll see a lot more of him with the bat, in particular, as he gains more experience.”
And of Elliott, he added:??”Grant hasn’t had a contract for a while but returns on the back of excellent recent form, including the World Cup. He’s a valuable member of our short-form sides.”
Among the other changes to their 20-strong contract list is the return of Doug Bracewell and the removal of spinner Ish Sodhi and batsman Colin Munro, who has been playing for Worcestershire in the County Championship.