Hallett was originally an
Australian rules footballer and once kicked eighteen goals for the Crown Street Public School against Ultimo. He graduated with Souths in 1908, the
first season of rugby league in Australia and made his debut in the first-grade team in 1909. Hallett was a playing member of three premiership-winning teams;
1909,
1914 and
1918. At the end of the 1914 season, Hallett was awarded a silver belt by the Sanderson Whiskey company as
Player of the Season. Hallett was first selected to play for New South Wales in 1911. In the same year he was selected to tour with the
1911–12 Kangaroo tour of Great Britain, making his debut playing against the
Northern Union at
Newcastle as a and scoring his one and only test try. He played the remaining two tests at fullback. Hallett toured with New South Wales to New Zealand in both the 1913 inaugural tour and 1914. Hallett's final year as a member of the national team was in 1914 when the Northern Union toured Australia. In a game against
Western Suburbs in 1924, Hallett was involved in a heavy collision, fracturing his jaw. Weeks later, he had surgery on his jaw. The scalpel from the surgeon however, left a permanent mark on the side of his face. ==Coaching career==