The Netherlands was in a tight spot from the start of their return match and, down 49-6, were knocked out for 105 for 23.3 ounces.
Thakshana was the main wicketkeeper, but seamer Dilshan Madushanka also contributed, 3-18.
The first goal was to qualify, and we accomplished it. The second goal was to win the tournament, and fortunately we did. We can go home happy, Sri Lanka coach Chris Silverwood told reporters.
The confidence we showed in this tournament we can take with us to the World Cup.