At the end, Blake Johnston was carried on the shoulders of friends up Cronulla beach in south Sydney, describing himself as "pretty cooked".
Johnston began surfing early on Thursday morning in aid of mental health awareness.
His effort has raised some A$335,000 (£185,000; $225,000) for charity.
With spotlights to illuminate a section of Cronulla's surf known as "The Alley", Johnston kept going overnight and had ridden over 700 waves by the end.
The previous record of 30 hours and 11 minutes was held by South African Josh Enslin.