Matthew King of Heal the Bay said the council voted 4-0 Tuesday night to approve the ban which affects most retail outlets in the city beginning in September.
Under the ordinance, plastic bags will no longer be available at any retailers in Santa Monica except restaurants providing food and liquids for takeout.
Shoppers who forget their reusable bags can purchase paper bags at checkout for at least 10 cents each.
In December, Gov. Arnold Schwarzenegger said he wanted to renew a push for a statewide ban the bags. Santa Monica joins other areas in California that have similar bans, including parts of Los Angeles County, Marin County and the city of San Jose.
The city of Calabasas will consider a ban on plastic bags on Feb. 1.