The group estimated that more than 870,000 people are living in poverty as it launched a new appeal to raise awareness of the problem.
The Scotland's Outlook campaign said a fifth of children are living below the breadline and highlighted figures showing that 23,000 people turned to food banks to feed themselves in the last six months.
A "perfect storm" caused by welfare reform, low wages, soaring bills, job insecurity and rising living costs had contributed to the scale of the problem, the campaign said.
It brings together Macmillan, Shelter Scotland, Oxfam, Alzheimer Scotland, Children's Hospice Association Scotland (Chas), Child Poverty Action Group (CPAG), the Poverty Alliance and the Scottish Council for Voluntary Organisations (SCVO) in a call for action to tackle the problem.
Martin Sime, chief executive of SCVO, said: "With nearly a million people in Scotland living in poverty, we have a humanitarian crisis on our hands and we need everyone's help to tackle it.
"Thousands of people are turning to food banks, struggling to heat their homes, and to clothe themselves and their children. It's not right.
"We want people to wake up to the poverty storm that's engulfing Scotland and get active in the fight against it."
Graeme Brown, director of Shelter Scotland, said: "People across Scotland are being battered by welfare reforms, stagnant wages, rising utility bills, higher living costs and job insecurity. For many, the safety and security of home is under threat like never before. It's a perfect storm on our doorstep.
"We see and hear the misery poverty causes every day. Not only does it have a devastating impact on home life, it has long-term detrimental effects on people's health, well-being and life chances - especially children.
"Set against the background of 155,100 households on council waiting lists and nearly 40,000 homelessness applications last year, it is clear that much more needs to be done to combat the root causes of poverty if we are to improve the prospects for everyone living in Scotland."
Jamie Livingstone, acting head of Oxfam Scotland, said: "Cuts to social safety-nets have gone too far, leading to destitution, hardship and hunger on a large scale.
"Too many Scots don't even have enough to eat - such glaring inequality simply cannot continue. And poverty isn't just affecting those out of work, for too many people employment is not a route out of poverty either.
"We need a society where everyone, whether they are in or out of work, has a decent income that allows them to live with dignity. We should expect nothing less in rich Scotland."