The two men and one woman, aged between 29 and 65, are accused of violating the Election Ordinance, which bans the incitement of others not to vote, or to cast an invalid vote during the election period.
The ICAC said its officers seized a number of mobile phones.
The suspects have been released on bail.
The anti-graft body said more law enforcement action may be taken as investigations continue.
“The ICAC will take resolute enforcement actions to combat conduct manipulating and sabotaging the election,” the ICAC said in a statement.
The maximum penalty for breaching relevant sections of the Elections (Corrupt and Illegal Conduct) Ordinance is three years in jail and a fine of HK$200,000.