The Bangladesh batter edged out competition from Ireland captain Gaby Lewis and USA pacer Tara Norris to claim the honour.
Mostary amassed 229 runs in her first six matches at the Qualifier, averaging 45.80 with an impressive strike rate of 145.85, playing a central role in Bangladesh’s unbeaten run.
She produced her highest score of the tournament, 59, in a decisive 39-run victory over Thailand, a result that sealed Bangladesh’s place in the main event scheduled for June and July.
Her performance earned her the Player of the Match award. Mostary continued her fine form with a fluent 47 against Scotland in the following game.