Playing at the Krira Shikkha Protisthan No 3 Ground, West Indies made 144 for 3 off their 20 overs, Dottin smashing 78 from 48 balls.
In reply, Australia lost early wickets and were never really in the hunt, finishing on 128 for 7.
Off-spinner, Anisa Mohammed picking up three for 25 and left-armer Shanel Daley claiming two for ten.
West Indies lost Natasha McLean (7) and Kycia Knight (18) to slip to 30 for two in the sixth over before Dottin came to their rescue.
She was at the foundation of two partnerships, adding 64 for the third wicket with Kyshona Knight who scored 21, and a further 50 off just 29 balls for the fourth wicket with Stafanie Taylor (11 not out).
The ladies play their opening game on Monday against England.