Hewitt, 16, outplayed South Korean qualifier MooBeen Kim to book his first win at Melbourne Park on Saturday after bowing out in round one of qualifying for the senior tournament last week.
The son of Australian great and Davis Cup captain Lleyton, Hewitt teamed with fellow home hope Duje Markovina in the boys doubles on Sunday.
In round one they took on Zangar Nurlanuly of Kazakhstan and India's Kriish Tyagi and, after losing the first set 6-2, they levelled by taking the second set 6-1 before losing the match tie-break 10-4.
Markovina, 17, grew up in Croatia but recently switched allegiance to play for Australia with his mother, who previously lived in Sydney, a citizen.
He enjoyed a singles win earlier on Sunday, beating Japanese qualifier Hyu Kawanishi 4-6 6-1 6-4.
In other results, Queensland 16-year-old Tahlia Kokkinis upset 10th seeded Bulgarian Rosita Dencheva 6-3 6-2.
Another wildcard, 15-year-old Victorian Ymerali Ibraimi eliminated Brazilian Pedro Albuquerque Dietrich 7-5 6-3
Australian players to bow out in round one included wildcard Jeffery Strydom, Ty Host, Alana Subasic, Tori Russell, Koharu Nishikawa, Emilie Chen and under-18 national champion Sarah Mildren, who had a three-set loss to Czech 11th seed Jana Kovackova.
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