Mr McCabe, from Marino in Dublin, was a spokesperson for community drug groups for more than three decades, according to the Irish Examiner.
He was a central figures in projects like the Inner City Organisations Network and the CityWide Drugs Crisis Campaign.
These projects were centrally involved in responding to the second heroin epidemic that devastated working-class communities in the early to mid 1990s and demanding, through street campaigns, action from the Government.
As has been pointed out by his family, Fergus McCabe chose hope over cynicism, and dedicated his life to the pursuit of social justice and equality.
This campaign, along with with the murder of journalist Veronica Guerin by the John Gilligan drug gang in June 1996, resulted in a raft of new legislation, including the setting up of the Criminal Assets Bureau.
In more recent years, Mr McCabe served on the National Oversight Group on the implementation of the National Drugs Strategy in the Department of Health.
The President said Mr McCabe dedicated his life to the pursuit of social justice and equality, and that his family could be extremely proud of the legacy he has left.
The great gift of Fergus McCabe was his genius in moving commitments on paper into the practical lives of members of communities.
President Higgins said Mr McCabe was "part of the beating heart of community campaigning in inner-city Dublin."
"Those of us who knew him will remember his energy and passion for justice, in making the case for inclusion and equality.
"As has been pointed out by his family, Fergus McCabe chose hope over cynicism, and dedicated his life to the pursuit of social justice and equality.
"With his vision and energy, he advanced the goals of countless initiatives, including the Inner City Organisations Network, the CityWide Drugs Crisis Campaign, Young People At Risk, the Ministerial Task Forces on Drugs and other national strategies to reduce the prevalence and impact of substance abuse," President Higgins said.
"The great gift of Fergus McCabe was his genius in moving commitments on paper into the practical lives of members of communities.”
