The Boomtown Rats frontman leads calls for mental health care funding to be protected, and made equal to investments for physical health, when a Government spending review is announced on 25 November (15).
The celebrities, including Steve Coogan, Emma Thompson and Richard E. Grant, outline 10 concerns that need to be addressed in a full-page advertisement titled "Equality for Mental Health", which was published in Britain's Daily Telegraph on Monday (02Nov15).
An extract from the letter reads, "We, the undersigned, have joined together to mount a cross-party, cross-society campaign aimed at persuading the Government to help reduce the suffering of those with mental ill health by increasing investment in the provision of mental health services...
"Ministers have accepted that whatever improvements in attitude may have been made in British society, those who experience mental ill health still do not get a fair deal from our health services. In effect, they suffer discrimination in our publicly funded NHS. This must be addressed...
"We urge the Government to seize the opportunity to end this historic injustice and commit to the investment that will lead to an economically, and socially, stronger Britain."
Geldof has a personal connection to the cause as his first wife Paula Yates battled depression and drug addiction for years before her death from a drug overdose in 2000.
Their daughter Peaches also had drug problems, and died in a hauntingly similar way in 2014, while their other daughter Fifi also suffers from depression.