Police said Sydney went missing in the Conical Hill area at Hanmer Springs yesterday.
He was reported missing and Land Search and Rescue teams started looking for him in the area.
He was found on Monday morning, police said in a statement about 10.30am.
"The 78-year-old man reported missing in Hanmer earlier today has been located safe and well.
"Police wish to thank the LandSAR teams for their efforts, and the public for all your shares."
Earlier today police said Sydney's loved ones had "concerns for his wellbeing" and a public appeal was made to help locate him.
LandSAR then started searching the area where Sydney was mountain biking.
-APL