Irish jockey John Egan and South African jockey Robert Fradd were both suspended last month by the Hong Kong Jockey Club, following their arrests in a case that also included charges of illegal bookmaking activities.
The jockeys had been free on bail since their arrests but told Hong Kong's Independent Commission Against Corruption on Tuesday that they would not accept bail any more, and they were freed.
"They refused because they haven't done anything wrong," said Egan's attorney, John McNamara.
Independent Commission Against Corruption spokeswoman Charmaine Mok confirmed the jockeys have not been charged but said they are still under investigation. The anti-graft body has obtained a court order to retain their travel documents, Mok said.
Nineteen more people - including four Jockey Club workers, the former racing editor of the English-language South China Morning Post and an alleged illegal bookmaker - were also arrested in the investigation. None have been charged.
The Hong Kong Jockey Club, which holds a monopoly on local horse racing, declined comment on the case. Jockey Club spokesman Raymond Wong also declined to say whether the jockeys can start racing again after their suspensions end Friday.