Jarvis was the only Zimbabwean bowler to claim a wicket and he was also responsible for dislodging Guptill with his right-armers.
McCullum and Guptill powered the New Zealanders to 187-3 from their 18 overs, after two overs were lost for each side due to wet ground conditions at the start of play.
"We started off very well in the first Twenty20 and to back it up with a batting and bowling performance like that is very pleasing,'' Guptill told APNZ from Zimbabwe.
"It's given us some good momentum going forward for the rest of the series.''
In pursuit of more than nine runs per over, the home side batted with plenty of intent as the 25-year-old opener Chamu Chibhabha carved an impressive 65 from 39 balls and he found good support in Elton Chigumbura who made 39 from 22 deliveries.
But, if Brendon McCullum was impressive with the bat, his older brother Nathan took his chance to shine with the ball.
The 31-year-old from Otago took three wickets, including the scalps of Chibhabha and Chigumbura to ensure Zimbabwe wouldn't threaten an unlikely victory.
Youngster Doug Bracewell also bagged a treble of wickets as he wrapped up the tail in his final over and the Central Districts all-rounder continued to win praise from his older teammates.
"Doug's been fantastic for us,'' Guptill said.
Northern Districts' seamer Graeme Aldridge made his full international debut after numerous tours with the national A side, although his first game in a Black Caps' uniform didn't go completely to plan as his four overs disappeared for 45 runs.
He did manage to pick up a wicket and a catch though.
Both sides switch their focus to the 50-over format now with three one-dayers awaiting them.
The first is to be played in Harare on Friday morning (NZT) with the second two days later before the third one-dayer will be contested in Bulawayo on October 25.
Scoreboard:
New Zealand Innings
Brendon McCullum b Jarvis 64
Martin Guptill c Chibhabha b Jarvis 67
Jesse Ryder not out 30
Ross Taylor run out 8
Extras: (6lb, 9w, 3nb) 18
TOTAL: (for three wickets in 18 overs) 187
Did not bat: Rob Nicol, James Franklin, Nathan McCullum, Jacob Oram, Doug Bracewell, Graeme Aldridge, Luke Woodcock.
Fall of wickets: 1-120, 2-172, 3-187.
Bowling: Chris Mpofu 4-0-40-0 (3w), Kyle Jarvis 4-0-36-2 (2nb), Ray Price 4-0-34-0 (1w), Elton Chigumbura 2-0-17-0 (1w), Prosper Utseya 3-0-45-0 (1nb), Chamu Chibhabha 1-0-9-0.
Zimbabwe Innings
Hamilton Masakadza c B McCullum b Bracewell 9
Chamu Chibhabha st B McCullum b N McCullum 65
Brendan Taylor b Aldridge 1
Elton Chigumbura c & b N McCullum 39
Charles Coventry c & b N McCullum 0
Forster Mutizwa run out 22
Malcolm Waller c Taylor b Oram 12
Prosper Utseya not out 2
Ray Price run out 0
Kyle Jarvis c B McCullum b Bracewell 0
Chris Mpofu b Aldridge b Bracewell 0
Extras: (3lb, w1) 4
TOTAL: (all out) 154
Fall of wicket: 1-24, 2-27, 3-84, 4-84, 5-125, 6-149, 7-154, 8-154, 9-154, 10-154.
Bowling: Doug Bracewell 3.5-0-25-3, Graeme Aldridge 4-0-45-1, Jacob Oram 3-0-27-1 (1w), Luke Woodcock 2-0-20-0, Nathan McCullum 3-0-23-3, Rob Nicol 1-0-11-0.