Garcetti argued that the move would pull working families out of poverty.
The law would raise minimum wage to $10.50 in July 2016, followed by annual increases to $12, $13.25, $14.25 and finally $15. Small businesses and some nonprofits have an extra year to phase in the increases.
Seattle, San Francisco and Chicago passed similar laws that would require each state to eventually lift the minimum wage to $15 an hour.
Last week, the California senate voted to hike the minimum wage to $13 per hour by 2017.