The Hong Kong Jockey Club has cancelled Wednesday night's meeting at Happy Valley, after calls online for protesters to disrupt the races.
Anti-government protesters had suggested the meeting should be targeted because a horse co-owned by pro-Beijing legislator Junius Ho was due to run in the first race.
"The race meeting at Happy Valley Racecourse tonight has been cancelled in view of the imminent threat to the safety of racegoers, jockeys and employees, and to the welfare of racehorses," the Jockey Club said in a statement
“Our concerns are tied to potential social unrest in the vicinity tonight, the very real threat of a disturbance or possible violence," the statement said.
“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."
The Jockey Club said it would announce details in due course regarding refunds for bets placed.
Ho has been accused of backing a gang of men who attacked MTR passengers at Yuen Long Station in July.
He has also been pushing for action against any school children who support the ongoing protests.
Earlier in the summer, a group of people affiliated with the horse racing industry petitioned the Jockey Club to cancel Ho's membership and to ban his horse, Hong Kong Bet, from all races.