They have replaced all-rounder Andre Adams and batsman Mathew Sinclair in a 20-man list of contracted players.
Gillespie was a member of the Black Caps squad which recently reached the World Cup semi-finals.
Hopkins appeared in five one-day internationals in 2004 and will provide back-up for first-choice wicket-keeper Brendon McCullum.
Team manager Lindsay Crocker stressed that the door was not closed on players who failed to make the list.
"Players who have missed out on contracts can play their way into the Black Caps through domestic performances, and can expect to pick up major association contracts," he said.
Shane Bond, Stephen Fleming, James Franklin, Peter Fulton, Mark Gillespie, Gareth Hopkins, Jamie How, Brendon McCullum, Craig McMillan, Hamish Marshall, Chris Martin, Michael Mason, Kyle Mills, Jacob Oram, Michael Papps, Jeetan Patel, Scott Styris, Ross Taylor, Daniel Vettori and Lou Vincent.