Hong Kong's Jockey Club called off races on Wednesday, just hours before the event was to start because of fears that protesters could compromise the safety of its staff, customers and horses.
Pro-democracy protesters had earlier threatened to target the Happy Valley race event as it was supposed to feature a horse belonging to pro-Beijing lawmaker Junius Ho.
The controversial figure was thrust into the limelight when he publicly defended the white-clad men who indiscriminately attacked civilians in Yuen Long in July, while he was also filmed shaking their hands and thanking them, the South China Morning Post reported.
"Our concerns are tied to potential social unrest in the vicinity, the very real threat of a disturbance or possible violence at Happy Valley Racecourse, and uncertainty regarding transportation in and around the area," said a Jockey Club spokesperson.
"This is a very difficult and most unfortunate decision to make, but public safety is of paramount importance to the club. We hope the racing community and the Hong Kong public will understand our reasons for doing so."
It is the latest blow to Hong Kong's economy linked to a political crisis that has lasted for months. Pro-democracy protesters in the city have taken to the streets for 15 straight weekends.
According to the daily, the Jockey Club had a discussion with Ho about potentially withdrawing his horse from the race, but he didn't budge.
The unrest has affected other sectors of Hong Kong's economy, including the city's restaurant and hotel industry. The international airport was also briefly shut down last month.
Mass demonstrations began in early June in opposition to a contentious extradition bill that would have allowed Beijing to nab "fugitives" seeking refuge in Hong Kong and try them in the mainland, under a system without safeguards.
Hong Kong's Chief Executive Carrie Lam announced the formal withdrawal of the extradition bill on September 4, but it has failed to mollify discontented citizens who insist the authorities respond to all five demands, which include introducing universal suffrage and setting up an independent body for an inquiry into alleged police brutality.
The city's economy is already under pressure from the US-China trade war and slowing consumption in China. The government announced last month that it is pumping billions of dollars into the economy to avert a recession.