The game in Nelson was decided under the Duckworth-Lewis method after wet weather set in with the West Indies apparently heading for their second consecutive heavy defeat.
A timely return to form for opener Martin Guptill, who made 81, saw New Zealand make 285-6 in their 50 overs and the West Indies were 134-5 after 33.4 overs when the rain sent the players from the field.
New Zealand, who won the Test series 2-0, now lead the ODI series 2-1 with one match to play in Hamilton next Wednesday.
He crawled to eight off 40 deliveries before cracking his first boundary when he drove a full-length Dwayne Bravo delivery back over the bowler's head and beyond the sightscreen.
From there, man-of-the-match Guptill never looked back as he batted at nearly a run a ball for the remainder of his innings, which included four fours and two sixes.
Jesse Ryder, fresh from cracking the world's sixth-fastest ODI century in New Zealand's rollicking 159-run victory in the third one dayer on Wednesday, survived two scares to score the bulk of the early runs.