From the Wanderers Rugby Union Club in Newcastle, he first represented for the Wallabies age 18 as Fly-half.
For the next five years he was a consistent selection for Wallaby Tests and tours and formed a formidable partnership with scrum-half Ken Catchpole.
In 1967, he joined Randwick to pair with Catchpole at club level and he played further Tests that year.
In 1968 Hawthorne accepted a then record $30,000 contract to switch to the professional code and join the St. George Dragons.
He played fifty-six games for the Dragons from 1968 to 1971 at Five-eighth before he joined Eastern Suburbs for his final season in 1972.