Hi Vivek Tiwari! I've just moved to Europe from Australia, so a couple Aussie ones jump to mind immediately.
One is Domino’s Pizza Enterprises Limited, which is the largest franchise holder from Dominos Pizza (basically covering Australia and New Zealand, Japan, and several countries in Europe). They're headquartered in Brisbane and I know some of the folks that worked with them. They launched a new machine learning based solution this year that allows people to get their pizzas delivered in under 10 minutes, by actually predicting the order before it happens! It's really cool - you can read more on the case study here.
Another one that's close to my heart - and a lot of people in tech - is Atlassian. If you search you'll find lots of stories about the ways they use AWS. One mentioned in this case study is how they used Amazon EC2, Elastic Load Balancer, and Amazon Elastic File System to create JIRA Data Center, a new enterprise version of their flagship application. Not only does it run on AWS, customers can use a CloudFormation template to deploy JIRA Data Center clusters themselves.