Brown's first entry onto a FIDE-rated competition leader board came in May 2006 when he came second in the Belconnen Premier with 5/8. He gained valuable experience, if not placements, in the 2006 World U14 and U16 Championships in 2006 and 2007, the Australian Open 2007, several editions of Australia's premier weekender, the Doeberl Cup, before he placed outright 3rd in the Australian Junior in 2008. His 6.5/10 in the 2nd Queenstown Chess Classic (2009) earned him 77 ELO points and an IM norm, while his first tilt at the World Championship cycle in the 2009 Zonal earned him a score of 5/9. His first serious victory was in the 2009 Australian Young Masters where he won by 1.5 points ahead of the field with 7.5/9. This was followed by 2nd in the 2010 Australian Junior Championship behind Bobby Cheng and =4th in the 2011 Australian Open, half a point behind the joint leaders GM Zhao Zong-Yuan, IM George Xie Wendi, and FM Moulthun Ly alongside IM Vladimir Smirnov. His best result so far followed immediately when he came 2nd behind Zhao Zong-Yuan in the 2011 Oceania Zonal, scoring a stunning 7/9 with a 2500 performance rating and earning him his IM title on the basis of that result alone.

Since then, in 2011, he has competed in the Sydney International Open scoring 5/9, the NSW Open (3.5/7), the Dutch Open (5/9), the 15th Hogeschool Zeeland Tournament in Holland (5.5/9), the e2e4 Sunningdale Masters B in England (3/9), BDO Chess Tournament Challenger (4/9) and the Caissa International (2/9). He finished up 2011 with =3rd at the Melbourne Cup Weekender in November and =4th at the Australian Young Masters in December. 2012 started with 5/9 (+4 -3 =2) at the Queenstown Chess Classic (2012). In February 2012, he came 2nd in the ANU Masters and won the ACT Championship. In June 2012, he had another stunning result, scoring 6.5/7 (TPR: 2633) to take outright first at the NSW Open. In August, he scored 6.5/13 at the World Junior Championship (2012) held in Greece and in November a strong 3rd place with 7/9 at the MCC Cup Weekender 2012 held in Melbourne. He finished 2012 poorly with 3.5/7 at the Lidums Australian Young Masters 2012 held in Adelaide, shedding some 28 ratings points, but immediately regained all of them, plus more, when he scored 7/11 in the Australian Championship held in January 2013. The next month, in February 2013, he came 2nd in the ACT Championship with 5/6 and immediately followed up with a powerful win with 8/9 at the ANU Masters. In March and April, however, he scored a meagre 4.5/9 at the annual Doeberl Cup held in Canberra over the Easter Weekend.

Brown's rating as of 1 June 2013 is 2291, and he is therefore the number 24 player in Australia. His rapid rating is 2301.