The Oxford-Cambridge boat races went ahead after a shell - which at first was believed to be a World War Two bomb - was removed from near the starting line.
Police were called on Saturday when a member of the public spotted the object in the River Thames near Putney Bridge, close to the race's starting line.
Scotland Yard said marine experts examined the shell and it was removed by specialist officers on Sunday morning.
Chief Inspector Tracy Stephenson said: "I'm very happy to update that the ordnance has now been safely removed and the race will be going ahead as planned.
"We have been working very closely with the organisers of the boat race to plan this event, which is eagerly awaited by spectators and supporters alike."
Thousands of people lined the banks of the Thames to watch the race between the two universities.
The women's race was won by Cambridge, while Oxford won the men's.
A spokeswoman for the event said the race was only ever called off during the two world wars.