It was first won by JR Hart riding Chief Lochiel 116 years ago and remained in the Hart family for three generations.
Hart"s great granddaughter flew down from Wellington to give the cup back to the club, president Nigel Rooney said.
"To come back to us well after 100 years, I mean holy hell.
"A bit of racing history coming back to Oamaru. It"s impressive, I love it."
He said Mr Hart was paid 30 guineas for his win which "would've been quite a bit of money in its day, I"d imagine".
The other Oamaru Cup the club has was first contested in 1929.
While it has been engraved with the winners each year, the cup stays with the club and the winners are presented with their own version to keep.
"This one [from 1909] has sort of trumped it a wee bit, being a bit older," Rooney said.
Yesterday"s race day was also the 150th anniversary of the club.
While it has had "all sorts of different names" throughout the years, the first recorded race of the Oamaru Jockey Club was in 1875.
"It"s come and it"s gone at times and had a few changes in names," Rooney said.
"We"ve had a checkered past. We"ve looked like at times that we wouldn"t be able to continue racing and to make it to 150. It"s huge for a little old town like Oamaru. Looking forward to the next 150."
