Hawkesby attended Auckland Grammar School in 1964. His started his broadcasting career in 1972 when he researched and presented Radio New Zealand's "Reflecting On" programme. This programme achieved six Mobil Radio Awards for "Excellence in Broadcasting". In 1986 Hawkesby moved to Radio Hauraki and read the breakfast news. In 1977 he joined TV2 as newsreader and in 1981 presented the top rating Top Half regional news programme for TVNZ. Hawkesby went on to host the popular It's in the Bag programme with co-host Hilary Timmins. In 1992 Hawkesby moved to TV3 as newsreader and in 1995 and 1996 was voted "TV Guide's People's Choice "Best Presenter", and "Best Newsreader". On Monday February 16, 1998 Hawkesby left TV3 after the introduction of a co-anchor. He was due to start presenting alongside Carol Hirschfeld, but pulled out at the last moment. John Campbell filled his place at the last minute.
For 3 weeks in January–February 1999, in a controversial move, Hawkesby became a weekday newsreader for ONE News, replacing Richard Long (who moved to presenting weekend bulletins alongside Liz Gunn). TVNZ's reason for this change was to try and capture some of the chemistry that Bailey and Hawkesby had during their days presenting Top Half. The change was short-lived, Long returned to the weekday bulletins, presenting alongside Bailey and Hawkesby received a $5.2m payout. In 2005 the highest paid New Zealand newsreaders received $800,000pa.
In August 1997, Hawkesby published "Save The Last Dance For Me".
Since leaving the broadcasting industry, Hawkesby has been active in the New Zealand wine scene as a judge and reviewer.  He was made a Member of the New Zealand Order of Merit in the 2011 Queen's Birthday Honours, for services to broadcasting and the community.
- "TVNZ salary saga ripped me apart, says Bailey". Herald on Sunday. 1 January 2006. Retrieved 7 October 2011.
- Anchorman: The Legend of John Hawkesby from Jono and BEN at Ten
- "The Queen's Birthday Honours 2011". Department of the Prime Minister and Cabinet. 6 June 2011. Retrieved 6 June 2011.