The promises of M&S, Royal Mail and the Co-op raise hopes the funds of other big businesses will also go green.
More than £1.5trillion of UK pension savers’ investments are in schemes without net-zero commitments.
But the move by the big three will see more than £30billion of pension pots helping save the planet.
The trio are committing to halving the emissions of their investments by 2030 at the latest, in line with the Paris Climate agreement.
They insist it will show it is possible for older final salary pension schemes to turn green.
M&S’s plans are the most ambitious, targeting net-zero by 2040. Royal Mail and Co-op are committing to Paris-aligned 2050 targets.
Comic Relief founder Richard Curtis, who launched financial campaign group Make My Money Matter, hopes it will persuade other firms to follow suit.
Mr Curtis – who wrote blockbuster Four Weddings and a Funeral – said: “Over the past year, we have woken savers up to the power of their pension and seen more than £1.2trillion committed to tackling the climate crisis.”
“M&S, Royal Mail and Co-op are showing the rest of the sector it can be done. We are calling on all remaining schemes to follow in their footsteps.”
Make My Money Matter claims for every £10 put into UK pensions, £2 is linked to deforestation.
M&S pension trust boss Simon Lee said: “A challenging journey lies ahead and it’s not something we can do alone, governments, financial institutions, our advisers and investment managers will need to play their part.”