Each year, as part of the Cadbury Chocolate Carnival, 30,000 Jaffas are rolled down the Northeast Valley street.
Prizes are awarded to the owners of the winning Jaffas.
Proceeds from the event this year will go to Parents Centres New Zealand and the Malcam Charitable Trust.
Cadbury events co-ordinator Lee-Anne Anderson said the fence would go up on Friday morning, before a street party started at 11am.
It was "mainly for safety, and to keep the Jaffas off the gardens".
Baldwin St residents had been notified about the street closure and the fence, she said.
Race-goers should not be concerned about having their vision blocked, as the fence would be comprised of steel tubes and a type of see-through fishnetting.
Holes had been drilled on both sides of the street and would be capped after the race and re-used each year.
