According to the party, the abduction occurred on Friday. On Saturday, the electoral commission is expected to declare current President Yoweri Museveni - who has been in power for 40 years - the winner of the general election held on Thursday.
In the post on X, Wine's party writes that he was taken to "an unknown destination." Party members have been unable to be reached for comment due to the internet blockade imposed by the government ahead of the election.
Uganda's military denied the abduction on Saturday morning, calling the reports "baseless" and "absurd."
Bobi Wine, a former singer, has emerged as Museveni's main challenger in recent years. With nearly 81 percent of the votes counted on Friday, the electoral commission said Museveni was leading with 73.7 percent of the vote to Wine's 22.7 percent.
Museveni, a former guerrilla soldier who seized power in 1986, has total control over the state and the security apparatus and has ruthlessly crushed all challengers during his reign.
