After winning the toss and electing to bat, the Sixers posted a total of 113 runs from their 20 overs. Ellyse Perry (25) and Sara McGlashan (23) led they way for the home side who were hampered by the loss of wickets at regular intervals.
Sarah Aley kept the Sixers in the match, after she started her spell with two wicket maidens and later removed the dangerous Naomi Stalenberg.
Aley finished with 3-11 from her four overs but still couldn't stop the Thunder from passing the Sixers' score with an over to spare.
The Sixers now sit in fourth place on the WBBL ladder, ahead of the fifth Perth Scorchers on net run rate.
The Sixers' next fixture is against the Brisbane Heat at the SCG on Thursday, January 18.