Annie Lennox has joined feminist campaigners and celebrities to promote women's rights on Mothering Sunday.
The singer made a passionate plea for gender inequality over the globe to be stamped out.
She said: "As a mother I've realised I've such a privileged life and I've seen the disparity, and I feel indebted and I feel that I must stand in solidarity."
Lennox was speaking at a rally organised by Care International, marking the start of the Walk In Her Shoes campaign, which encourages people in the UK to raise money for the charity by walking 10,000 steps a day for one week in March.
A crowd of hundreds packed the Scoop amphitheatre on London's South Bank to listen to speeches from survivors of female genital mutilation (FGM), politicians and feminist campaigners.
London mayoral hopeful Sadiq Khan, rights campaigner Bianca Jagger and International Development Secretary Justine Greening attended the packed event.
Lennox said she would not preach to others but applauded fellow public figures who have lent their support to the campaign.
She said: "Anyone living in this country that has access to the resources that we have are privileged. And therefore I feel if you want to contribute by all means, if you've recognised the difference for yourselves.
"I would encourage any woman or girl or man - I believe men also must be feminist, no doubt."
A crowd of suffragettes, in period dress, holding banners and wearing sashes emblazoned with the slogan "Deeds not words" sang and chanted feminist anthems.
Lennox added that feminists had historically faced challenges and praised the suffragettes for their bravery.
She said: "They were sacrificing themselves for us ... To have access to the democratic vote, to education, to job opportunities - the fight continues.
"The problem is in our country is we have amnesia. We forget that people sacrifice so much to give us the things we take for granted.
She said days like today were not just a "commemoration" but an "encouragement to keep this fire burning, this flame to illuminate the disparity to understand that there's so much disempowerment globally".
"And it's very hard to get that message through, because we're busy, we have our busy lives and our very comfortable existences.
"So we don't think about the world as it stands for millions of women who are uneducated and have no access to resources."
Crowds set off for a march alongside the River Thames following a series of rousing speeches.
They walked along the South Bank, over Southwark Bridge and back across the Millennium footbridge, accompanied by the sound of cheers and drums.
Dr Helen Pankhurst, great-granddaughter of suffragette Emmeline, was leading the procession.
She added that she felt "really honoured" and "proud" to be related to her revolutionary ancestor but warned "there is so much more to be done".
She said: "There is still a need for solidarity, there is still a need for activism - and also it's fun.
"It's about celebration, it's about being together, it's about sisterhood.
"We can do that in many ways, we can do that through social media but there is still a value in being out in the streets, walking together shoulder to shoulder as the suffragettes did 100 years ago."
Of Care International's campaign, she said: "Walk In Her Shoes symbolises the gruelling treks millions of women and girls make daily to collect water, at the expense of their education. When a girl's childhood is taken away, her future goes with it.
"And this year, of course, we'll also be thinking about the many refugees who have trekked hundreds of miles to find safety, many of them mothers, forced to carry their children from one danger zone to the next.
"I'll be walking with my daughter - we can't think of a better way to mark Mother's Day."