Police Scotland said he had been found in the River Oykel in Sutherland on Tuesday.
The man has still to be formally identified, but officers say the family of 80-year-old Ian McMullen, from Hertfordshire, have been informed.
Mr McMullen was reported missing on Thursday after he failed to return from a fishing expedition on the river near Oykel Bridge.
The body was recovered during searches conducted by the Police Scotland Dive and Marine Unit.
Chief Inspector Iain MacLelland said: “Our thoughts are with Mr McMullen’s family at this sad time.
“I would like to take the opportunity to thank the partner agencies and members of the public who have helped with our enquires and search activity.
“There are no apparent suspicious circumstances and a report will be submitted to the procurator fiscal in due course.”