Thursday's 4-3 vote came weeks after federal agents arrested the embattled mayor of New Jersey's capital on corruption charges. Authorities allege Mack agreed to accept bribes as part of a sting.
The council also voted 5-2 to introduce an ordinance cutting Mack's pay from $126,400 to $60,000. That provision must be acted on at a later council meeting.
The Times of Trenton reports Councilwoman Kathy McBride called the no confidence vote "nonsense" compared to the city's problems.
The mayor has told the council he doubts it has the authority to cut his salary.