The ewe, named Suzy by her captors, is believed to have never been shorn.
Suzy will be shorn at The Wool Shed, the national museum of sheep and shearing, in Masterton.
She will be shorn with blade shears by world record holder Peter Casserly, who also did the honours for Shrek, the famous Merino sheep found at Bendigo Station in 2004.
A competition will also be held to guess the length of the longest staple of wool and the weight of the fleece.
“We’ll be putting Suzy forward to the Guinness Book of Records,” Gavin Tankersley, chairman of the trust that administers The Wool Shed, said.
“We aim to establish a record for the longest staple of wool ever shorn from a sheep.”
Though she has an enormous fleece Suzy is a crossbred sheep so her total fleece weight is unlikely to beat the world record, which favours the Merino breed. The weight record was initially claimed by Shrek and is now held by Chris the Sheep in Canberra.
The event will take place at The Wool Shed, 12 Dixon Street at 1pm on Sunday.