After winning the toss and batting first - as they have done in every match in the tournament - Ireland ran up a formidable 225 for seven off their 20 overs at the Sheikh Zayed Stadium in Abu Dhabi on Saturday.
That proved to be too much for Afghanistan to chase down and, despite making a flying start to their reply, they were bowled out for 157 to suffer a 68-run defeat.
Both teams, who were meeting in the final for the third successive time with one win apiece previously, had already secured their place in the first round of next year's ICC World Twenty20 finals in Bangladesh but there was no sign of Ireland easing off as they ran amok with the bat.
After Ireland's win the International Cricket Council confirmed they would be placed in Group B in the first round of the World Twenty20.
The Irish have been grouped with Zimbabwe, Holland and the United Arab Emirates with only the group winner progressing to the Super 10 stage.
Afghanistan are in Group A alongside tournament hosts Bangladesh, Nepal and Hong Kong.