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 school's 1st grade cricket team. He was known to wicketkeeper 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).
Starc debuted for his home state New South Wales in 2009, at the age of 19. His performances for Western Suburbs and the state 2nd XI earned him the elevation and he replaced the suspended Aaron Bird for the final match of the season. Starc, gained a spot at the Centre of Excellence in the off-season in 2009. In eight Sheffield Shield games in the 2009-10 season he captured 21 wickets, including a best of 5 for 74 against Queensland, and also chipped in with a half-century.
In 2015, Starc maintained his dominance at the international level by breaking records in the Australian domestic one-day tournament, which came about due to postponement of Australia's tour of Bangladesh. The pure numbers from Starc's tournament underline his dominance: 26 wickets from six matches at an average of 8.12 and a strike rate of 12.3. Starc was named as Player of the Tournament.
After a series of injuries to several senior Australian fast bowlers, 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. Starc earned his first international call-up for Australia's 2010 tour to India, debuting in an ODI. In the Test series in India in 2013, he fell just one short of a maiden Test ton.
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.
Starc received the Man of the Tournament award in the 2015 Cricket World Cup, which Australia won, defeating New Zealand in the final. He also became Australia's leading wicket-taker across all forms of first-class and international cricket for the 2014–15 season with 60 wickets, including the leading wicket taker for 2015 Cricket World Cup, having played one fewer game than New Zealander Trent Boult.
In 2012, Starc was signed by the Sydney Sixers for the inaugural Big Bash League, followed by the Champions League T20. In the 2014 Indian T20 league, he was bought by Royal Challengers Bangalore and quickly became their key bowler in the IPL 2015 edition. After missing the beginning of the tournament with injury, he came back and continued on with his good form from the World Cup.  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.
On 18 January 2015 in an ODI match at MCG against India he became the first Australian to capture six wickets in a home ODI match with his best bowling figures of 6/43. Starc was the joint highest wicket taker in the 2015 Cricket World Cup along with Trent Boult with 22 wickets at an economy rate of 3.58, but he was judged to be no.1 having played one less game than Boult. Starc was adjudged Man of the Tournament in the 2015 Cricket World Cup.
In 2015, on day three of the Second Test between Australia vs New Zealand, Starc delivered his fastest ball at a rapid thunderbolt of 160.4 kph and joined the 160kph club. This happened in his 89th over. This also made another record of the fastest Yorker ever bowled by any bowler, and the fastest ball ever bowled in a test. After bowling at this rapid pace, he soon started bowling 150 kph plus. One of which, at 154.8 kph, smashed the corner of Brendon McCullum's bat.