Boston Mayor Michelle Wu opened her second week in office by signing an ordinance she had long championed: restricting city money from being invested in fossil fuel companies.

Before a crowd of environmentalists, city councilors and media Monday, Wu signed her first ordinance since being sworn in, prohibiting the city from holding investments in or further investing in companies that make more than 15% profits from fossil fuels, tobacco products or for-profit prisons and jails. The ban will go into effect by 2025.

"We're moving quickly to make sure that Boston will set the tone for what's possible for that brightest, greenest future for all of our kids," Wu said.

Wu said she and the council have been working since 2014 "to push for Boston to speak up, to stand out, to take action when it comes to divesting from harmful industries, divesting from fossil fuels and reinvesting into our own communities."

The new mayor said Environment, Energy and Open Space Chief Reverend Mariama White-Hammond is heading up many efforts with the goal of "truly linking our climate-just future with jobs, with a vision of Boston for everyone."

The city's largest investment funds are pensions governed by state, not city, law, limiting the ordinance's reach.

The council unanimously approved the ordinance last week. The new ordinance additionally requires the city to track its investments and report how it can reduce reliance on fossil-fuel investments and other companies outlined in the law.