Porterfield hit seven fours and a pair of sixes to lead his side past Holland's total of 139 for five with two balls to spare.
Alex Cusack (two for 14) helped restrict the Dutch to a slightly below-par total on a quick outfield at the Sheikh Zayed Stadium in Abu Dhabi.
Ireland play their final warm-up match against Papua New Guinea in Dubai on Wednesday before starting the World Twenty20 qualifying campaign against Namibia in Abu Dhabi on Friday.
Ireland are expected to reach next year's World Twenty20 in Bangladesh with six countries to qualify for the expanded 16-team tournament.
- Sports & Recreation
- Alex Cusack