A man who went missing in a flooded river in Mount Isa has been found safe and well more than a day after he disappeared.

Witnesses saw the man dive into the Leichhardt River on foot at the Twenty Third Avenue crossing at Happy Valley about 10:00pm on Friday but fail to resurface.

This morning, police questioned the 22-year-old Mt Isa local after a relative realised he fitted the missing person's description.

Constable Glenn Angel said the man admitted to taking the late-night swim across the waterway.

"When the male was spoken to by police, the male said that he was the one that entered the river to go for a swim and then swam towards the shore and exited the river," he said.

Emergency services searched both sides of the river down to the Isa Street Bridge for three hours after the man went missing but failed to find him.

The search resumed on Saturday morning with swift water rescue teams.

The search has now been called off.