The wicketkeeper-batsman's swashbuckling 79 from 44 drove Sri Lanka to 162 for six on a sunny afternoon at Kardinia Park before the talismanic Hasaranga helped restrict Netherlands to 146 for nine, despite an unbeaten 71 from opener Max O'Dowd.
The win put Sri Lanka top of Group A ahead of second-placed Netherlands, while knocking the winless United Arab Emirates out of the tournament.
Sri Lanka were stunned by Namibia in their first qualifier, but steadied their campaign by thrashing the UAE. "We knew that when we came to the World Cup we would be the favourites in this group," said captain Dasun Shanaka. "Unfortunately we missed out in the first game, but we regrouped and we came back strong. "I thought the wicket wasn't easy to bat on, it was a bit two-faced.
So I thought in the first 10 overs we were able to control the scoring rate really well." The Netherlands have a nervous wait for the late match at Kardinia Park between third-placed Namibia and the UAE.