Skipper Prithvi Shaw led from the front with a 94-run knock and shared a 180-run stand with fellow opener Manjot Kalra (86) to power India to a challenging 328 for seven.
There was no respite for the Australians even after their departure with Shubhman Gill tormenting the bowlers with his 63-run knock.
India pacers Kamlesh Nagrakoti (3/29) and Shivam Mavi (3/45) then impressed with their speed and shared six wickets between them to shot out Australia for 228 in 42.5 overs.
Nagarkoti hit the deck consistently at a speed in the range of 150kmph and was well supported by Mavi, who also clocked 145 at times. The two pacers tested Australians with their nagging off-stump line.
Australia opener Jack Edwards top-scored for his side with a 73-run knock after a steady start with Max Bryant (29) but struggled to find support from others.
Jonathan Merlo (38) tried his best in the middle order and stumper Baxtor Holt (39) resisted in a rearguard fight but both were undone by Mavi.
India next play Papua New Guinea on Tuesday.
Here are the highlights of India U-19 vs Australia U-19 match:
# India has defeated Australia by 100 runs in their first match of ICC U-19 World CUP 2018.
# OUT!! Shivam Mavi removes Xavier Bartlett. India is only two more wickets away from the massive victory.
# OUT!! K Nagarkoti to Will Sutherland, out Bowled!! At the brutal pace of 145 KMPH, Nagarkoti shattered the stumps.
# Score after 36 overs - Australia UU19: 175-6, Will Sutherland 7(3); Baxter J Holt 1(1)
# OUT again!! And the last hope of Australia is also down. A fighting innings of Jack Edwards comes to an end.
# One more blow, Austin Waugh is out. His father Steve Waugh and mother who are present at Bay Oval will be disappointed.
# Austin Waugh, right handed bat, comes to the crease. He is the son of Australia legend Steve Waugh.
# Out Uppal Run Out!! Yes-no and out. Are India now driving the game away from Australia's hold? Looks like that.
# Score after 31 overs: Australia U19 148-3, Jack Edwards 62(79); Uppal 3(4)
# Shivam Mavi to Merlo, out Bowled!! Wicket number three goes down for Australia.
# Score after 22 overs: Australia U-19: 89-2, Jack Edwards 43(60); Merlo 1(1)
# Abhishek Sharma to Jason Sangha: OUT! Big wicket for Australia as skipper Sangha goes back to the pavilion. India tightening its grip on the match.
# OUT!! Nagarkoti scalps Bryant. A good length bowl at the ridiculous pace of 144 KMPH. Bryant drives on the up but finds Mavi at short extra cover.
# Australia get the start they needed to chase such a massive target. Score after 9 overs: AUS U19 40-0, Bryant 18(31), Jack Edwards 22(23
# Jack Edwards and Bryant are at the crease. Jack Edwards is on strike. Shivam Mavi will open the attack
# India finish on 328/7 after their 50 overs and in doing so, put more runs on Australia than any other team in #U19CWC history.
India finish on 328/7 after their 50 overs and in doing so, put more runs on Australia than any other team in #U19CWC history.
Chase starts in half an hour!January 14, 2018
🇦🇺 🎯 329 for victory #INDvAUS
# 200 up for India! Shaw and Manoj provided India with the start they needed. Above 300 would be a good score here.
# Watch Jason Sangha's brilliant catch that sent Manoj back to the pavilion.
VIDEO ▶️ Australia remove the second India opener with Jason Sangha's catch taking care of Manjot Kalra for 86.January 14, 2018
# OUT! Manoj also misses his hundred. Another wonderful innings comes to a sad end. Manoj scored 86 runs.
# OUT! Prithvi Shaw misses a well deserved hundred. Poor shot it was. he is out on 94.
# Fifty comes up for skipper Shaw. What a wonderful innings this was. Except that no ball caught behind, Shaw gave no chances to the Aussies. Special innings this is.
# Australia will regret the no-ball bowled by Sutherland. After 16 overs scorecard reads: India 88/0
# OUT!! Up goes the finger. Skipper Shaw has to go. But wait, he has been asked to stay. Umpires are checking no ball. And Shaw will survive as Sutherland overstepped.
# Both openers provided India a great start. The score after five overs: India 25/0
# India win the toss and elect to bat first. A good decision by skipper Shaw.
# India U19 Squad: Prithvi Shaw, Manjot Kalra, Shubman Gill, Himanshu Rana, Abhishek Sharma, Ayush Juyal, AS Roy, K Nagarkoti, Shivam Mavi, Shiva Singh, Ishan Porel
# Australia U19 Squad: Max Bryant, Jack Edwards, Jason Sangha, Jonathan Merlo, Param Uppal, Austin Waugh, Will Sutherland, Baxter J Holt, Xavier Bartlett, Jason Ralston, Lloyd Pope