The 25-year-old will join compatriots Hamish Rutherford and Neil Broom at the County Ground.
Neesham has played in 13 Twenty20 matches, nine Tests and 19 one-day internationals for the Kiwis.
"He's an exciting talent and has the capability to win games with both bat and ball," said elite performance director Graeme Welch.
"To have three internationals, all of whom are team-mates in New Zealand, available for the entire T20 Blast campaign is massive and will provide us with stability on the field and within the dressing room."
Teams are normally allowed to play only two overseas players in the T20 Blast, but Broom holds a UK passport.
"The three of us being able to contribute as a unit is a big attraction and should give us a real head start," said Neesham, who has also played in the Indian Premier League for Delhi Daredevils.
Derbyshire have signed New Zealand all-rounder James Neesham for this summer's T20 Blast competition.