Chase made an unbeaten 42 off 27 balls as the tournament co-hosts sealed a five-wicket win with an over to spare, but it was not plain sailing as they chased down a modest target of 137.
When Sherfane Rutherford fell off the final ball of the 16th over, his side still needed 40 runs off the last four overs and the game appeared to be heading for a nail-biting conclusion.
But Chase showed no signs of nerves as he finished things off in relative comfort, hitting four boundaries and a six in his last seven deliveries in a dramatic gear shift.
PNG, ranked 20th in the world by the International Cricket Council, were asked to bat first and reached 8-136 after losing three wickets in the powerplay.
Their innings was built around a knock of 50 from Sese Bau, while wicketkeeper Kiplin Doriga chipped in 27 not out from No. 7.
Andre Russell and Alzarri Joseph took two wickets apiece for the Windies - the latter slightly expensive but responsible for cleaning up Bau - and Akeal Hosein one for nine in his three overs.
Alei Nao put early pressure on the home side when he had Johnson Charles for a golden duck before Brandon King (34) and Nicholas Pooran (27) chipped away at the target.
Papua New Guinea's bowlers kept pace off the ball as the scoring slowed and when Doriga collected a pair of smart catches standing up to see off captain Rovman Powell and Rutherford in quick succession, it looked like game on.
Russell smashed his fourth ball for six to kick-start the counter, before Chase opened his shoulders in a decisive 18th over. After claiming two for 10 from his first three overs, captain Assad Vala was taken for 18 in his last visit, leaving Chase standing tall at the close.
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