Aviva said it plans to become net zero in less than two decades, a move that is likely to put pressure on the companies that it invests in to change their practices.
The insurer manages around half a trillion pounds worth of assets including billions belonging to British pensions savers.
It will divest from companies if they do not meet its environmental standards.
Aviva will push the companies it invests in to report on their annual climate progress and engage with shareholders.
The pledge will “inform every aspect of operations and investment decisions at Aviva”, in what it said was the most ambitious net-zero plan of any major global insurer.
The insurer will aim to cut the carbon intensity of its investments by a quarter by 2025 and 60% by 2030.
By the end of 2022, it will have sold its shares in companies that make more than 5% of revenue from coal unless they have signed up to a pledge to Science Based Targets, an organisation that monitors companies’ commitments to emissions reduction.
“Aviva is taking bold steps to help tackle the climate crisis,” said chief executive Amanda Blanc.
“As the UK’s leading insurer, we have a huge responsibility to change the way we invest, insure and serve our customers. For the world to reach net-zero, it’s going to take leadership and radical ambition. And it is going to take Aviva to play our part.”
The company also plans to make major green investments. The Government decision to auto-enrol people into pension savings programmes has given the company £10 billion that it will invest in low-carbon strategies.