The buses must now hire a security guard to accompany parties and install cameras to keep watch on the revelers.
"Summer is coming," said Ald. Emma Mitts (37th). "Party buses are supposed to be for celebrations, not potential rolling cemeteries."
Mitts said that the proposed ordinance is not perfect and won't prevent people who are permitted by state officials to carry concealed handguns from boarding the buses while armed.
Either the owner of the bus or an employee "must take affirmative measures to determine that no passenger is illegally carrying a firearm," according to the proposed regulations.
Mitts said Chicago officials should petition state lawmakers to change state law.
The state's concealed-carry law prohibits weapons in bars, but it does not prohibit them on the buses, where alcohol can be served.
Ald. Brendan Reilly (42nd), one of the co-sponsors of the ordinance, said that loophole must be closed.
While most of the new rules would go into effect immediately, the requirement for security guards to be on board would start May 1, and cameras would be required on the buses by June 1.
Ald. David Moore (17th) cast the lone vote against the measure, saying the requirement for a security guard could cause more problems than it would solve by introducing a stranger into alcohol-fueled private parties.
The last-minute toughening of the rules was prompted after police found three semi-automatic handguns with extended magazines as well as drugs on an overcrowded party bus on Lake Shore Drive near the Museum Campus, according to a statement from police.
The latest crackdown was prompted by the shooting death of Quentin Payton, 28, of West Ridge. He died March 12 after a "verbal altercation" led to an exchange of gunfire between a dark-colored SUV and someone on the party bus after it stopped at the Dunkin Donuts at 6332 N. Broadway.
Two others were injured in the altercation.
About 370 party buses operate in the city, officials said.
The measure is also designed to give officials authority to impound buses operating without a license and increase the fine for that violation to $5,000. The buses would have to clearly display their license information.
Party buses that carry at least 15 people and allow drinking on board — or stop at multiple watering holes — would be forced to follow the new rules, which would allow the operators to end a trip immediately if a passenger refuses to obey the rules, according to the measure.
The measure also stiffen fines significantly, with the punishment for a first offense rising from $100 to $1,000. A maximum fine of $10,000 would be for multiple offenses.
In September, the Council passed an ordinance requiring drivers to call police if drunken patrons toss bottles from a vehicle, moon or flash passersby or use illegal drugs after a spate of shootings.
But that didn't stop the violence. Three people were injured in a December shooting aboard a party bus in Lakeview, the sixth party bus shooting with injuries in 14 months.