The win helped India stay atop the Pool B standings after remaining unbeaten in the league stage of the tournament.
A composed first quarter saw both sides cancel each other out in a midfield battle.
The home side pushed India onto the back foot early on, with the visitors conceding a penalty corner, but Vikas Dahiya's smart save ensured both teams went into the first break locked in a stalemate.
In the second quarter, Thundersticks captain Chris Bausor converted his team's second penalty corner giving them the lead.
Western Australia kept up the pressure, with another penalty corner but were again denied by Dahiya, ensuring India would go into halftime down by the single goal.
India stormed out of the blocks in the second half, and soon enough Sumit scored the goal to draw them level.
With both the teams locked at 1-1, the Indians came with fresh energy crowding the midfield and pushing Western Australia deep into defence.
With their first penalty corner of the game, Varun Kumar found the net, giving India the lead in the 39th minute. A minute later, he doubled the joy by converting another penalty corner to seal the deal in favour of the Indian team.
India played out the final quarter smartly and cautiously, avoiding needless fouls and turnovers to take a well deserved victory.
