He is also a former junior cricketer for the Berala Sports Cricket Club in Sydney, Australia, who attended Homebush Boys High School also representing the schools first grade team. He was known to wicketkeep and bowl in the same innings during his time with the club. Mitchell Starc was also a representative cricketer of the Northern District Cricket Association (NDCA).
After a series of injuries to several senior Australian pacemen, Starc was a late replacement in the team to tour India in late-2010, replacing Josh Hazlewood. Later Doug Bollinger was injured after the First Test, and that left Starc and fellow uncapped young pacemen Peter George and James Pattinson competing for a place. George was selected, and after Pattinson was injured, Starc made his ODI debut against India in Visakhapatnam in October 2010. He did not bat and was wicketless.
Starc made his Test debut for Australia on 1 December 2011 in the first Test of the two-Test series against New Zealand in Brisbane. He took two wickets in the match, and another two in the second Test in Hobart. He was left out of the squad named for the first Test of the subsequent series against India, but was recalled for the third Test on the pace-friendly WACA Ground in place of spinner Nathan Lyon, taking four wickets. During the 2011–12 Australian summer, Starc also played for the Sydney Sixers in the inaugural Big Bash League. The Sixers won the tournament and Starc finished as its equal third-highest wicket-taker with 13 in six matches. Starc was selected to play for the third test of South Africa's tour of Australia in 2012. Whilst Australia lost the match, Starc took 6/154 and achieved the second fastest test fifty (32 balls) by an Australian in Australia's second innings on 4 December. Despite his recent form, he was rested in favour of Jackson Bird to make his debut for the Boxing Day Test against Sri Lanka. They would both be selected for the Sydney Test a week later.