Fossil fuel divestment or fossil fuel divestment and investment in climate solutions is an attempt to reduce climate change by exerting social, political, and economic pressure for the institutional divestment of assets including stocks, bonds, and other financial instruments connected to companies involved in extracting fossil fuels.

Fossil fuel divestment campaigns emerged on college and university campuses in the United States in 2011 with students urging their administrations to turn endowment investments in the fossil fuel industry into investments in clean energy and communities most impacted by climate change. In 2012, Unity College in Maine became the first institution of higher learning to divest its endowment from fossil fuels.

By 2015, fossil fuel divestment was reportedly the fastest growing divestment movement in history. As of July 2023, more than 1593 institutions with assets totalling more than $40.5 trillion in assets worldwide had begun or committed some form of divestment of fossil fuels.

Divesters cite several reasons for their decisions. To some, it is a means of aligning investments with core values; to others, it is a tactic for combatting the fossil fuel industry; to others, it is a way to protect portfolios from climate-related financial risk. Financial research suggests that, in the longer term, fossil fuel divestment has positively impacted investors' returns.

Fossil fuel divestment aims to reduce carbon emissions by accelerating the adoption of the renewable energy transition through the stigmatization of fossil fuel companies. This includes putting public pressure on companies that are currently involved in fossil fuel extraction to invest in renewable energy.

The Intergovernmental Panel on Climate Change found that all future carbon dioxide emissions must be less than 1,000 gigatonnes to provide a 66% chance of avoiding dangerous climate change; this figure includes all sources of carbon emissions. To avoid dangerous climate change, only 33% of known extractable fossil fuel of known reserves can be used; this carbon budget can also be depleted by an increase in other carbon emission sources such as deforestation and cement production. It is claimed that, if other carbon emissions increase significantly, then only 10% of the fossil fuel reserves can be used to stay within projected safe limits.

Furthermore, according to the US Environmental Protection Agency, Earth's average temperature has risen by 0.78 °C (1.4 °F) over the past century, and is predicted to rise another 1.1 to 6.4 °C (2 to 11.5 °F) over the next hundred years with continued carbon emission rates. This rise in temperature would far pass the level of warming that scientists have deemed safe to support life on earth.

I think this is part of a process of delegitimising this sector and saying these are odious profits, this is not a legitimate business model ... This is the beginning of the kind of model that we need, and the first step is saying these profits are not acceptable and once we collectively say that and believe that and express that in our universities, in our faith institutions, at city council level, then we're one step away from where we need to be, which is polluter pays.