He was the national title holder of Manhunt Australia during 2007 and was also the face of Australian swimwear label Funky Trunks from 2004 to 2010.
He graduated from high school in 1991 and was awarded an outstanding sporting achievement award, recognising his sporting contribution, which included winning the athletics champion boy and swimming champion boy in his final year, only eight months after taking up competitive swimming.
He held the Victorian state short course record for the 50m Butterfly in the 35-39-year age division of the Masters Swimming Association, from 2010 to 2016.
[8] In February 2007, he represented Australia in the largest contested and most prestigious international male modelling competition in the world at the time, the Manhunt International 2007 World Final, held at the six star Kangwon Land Casino Resort, in South Korea, where he competed against a record 48 contestants from as many countries.
This led to other modelling offers and sparked an invitation to compete in the 2006 Manhunt Australia competition in which he won the national title the same year.
He appeared on the CD single covers for "Perfect Strangers" and "Hot Lovin'", written by Drew Heinemann and performed by Daniel McGahan and Natt Dunn in 2011.
Barnett was a contestant on the Network Nine television game show 1 vs. 100, hosted by Eddie McGuire, which aired on 9 July 2007.
Barnett appeared in the Australian series of the Network Ten reality television show Big Brother Australia 2008.
He entered the Big Brother house, which was located inside the Dreamworld amusement park in Queensland, on Sunday 4 May 2008 under his nickname Barney.
[14] Barnett has also made appearances in Australian television commercials, which include the Volvo "Attention Seeker" TVC, televised to a global audience until 2012.,[15] Target TVC March 2012, Bike Exchange 2012, iiNet 2013, Funky Trunks Underwear 2013, Holden Storm 2015, and 5digitalquotes.com.au 2015.