The ordinance also prohibits lighting up at light-rail stations, within 25 feet of bus stops and within 50 feet of gatherings of 100 or more people on city grounds.
While Anderson said the ordinance would take effect "immediately," it actually must be published in the two daily newspapers before it will be enforced.
Even then, police won't be on the lookout for smoking scofflaws. They would enforce the law only when they encounter smoking during their routine duties. Smokers could be fined no more than $25.
Noting that the Environmental Protection Agency has found no acceptable level of exposure to class A carcinogens - such as secondhand smoke - Anderson said the ordinance will "protect the well-being of city residents."
Supporters also hope it will encourage smokers to kick the habit.
"It's an extremely difficult addiction to get beyond," Anderson, a former smoker, acknowledged. "But it is absolutely worth it."
The mayor was flanked by a dozen supporters, including an official with the American Cancer Society, who presented the city a plaque of appreciation.
City Councilwoman Nancy Saxton, who is running for mayor, also attended.
The former respiratory therapist noted secondhand smoke can aggravate asthma or cause it.
"We have two classes of people: People who smoke and people who don't. They need to coexist," she said, adding that banning outdoor smoking doesn't violate the rights of smokers.
The council unanimously approved the smoking ban earlier this month.
Utah's capital joins an estimated 600 cities nationwide that have restricted outdoor smoking, including at least nine in the state: Clinton, Hyde Park, Logan, Midvale, Riverton, Sandy, South Jordan, Spanish Fork and West Jordan.