Ness is known for his contributions regarding worker's movements and party formation in the Global South, and has worked with leading activists in India, Southern Africa, East and Southeast Asia.

Most notably, he worked with Mexican workers, unions, and community organizations in New York City to establish a Code of Conduct for migrant laborers in 2001 who were paid below minimum wage.

[citation needed] In 2013, he was a member of an eight-member delegation of the International Commission for Labor Rights investigation of worker repression in India’s auto industry.

During this period, he learned to advocate on behalf of disconnected jobless workers to organize their own association directly at New York State unemployed offices.

In this way, in 1998, he co-founded the Lower East Side Community Labor Coalition in New York City with members of progressive and leftist local groups, which mobilized low-wage workers with support of UNITE Local 169, a labor union in the neighborhood that was previously affiliated with the Amalgamated Clothing and Textile Workers Union.

[21] He helped organise large Mayday demonstrations in New York City, centered around authentic-worker led mobilizations for immigrant rights from 1999 to 2001, often culminating in mass arrests of street theatre and protests by New York City police, setting a precedent of immigrant leadership and participation in the US organization of the annual worldwide labour holiday.

Yet Ness maintained, “In India, the major contradiction and division is the difference between permanent and contract, and it plays itself out in furthering the super exploitation of the labour force of this country.”[24][25] Ness was elected chair of the Professional Staff Congress City University of New York (PSC/CUNY) International Committee in September 2016 and has been chair of the United States Peace Council in May 2018, advocating for working-class solidarity and against war and imperialism.

Much of his organizing, advocacy, and research since 2015 has focused on a rejection of utopian and idealist notions propounded by social democrats, anarchists, Western Marxists, and through applying an anti-imperialist state-centered Marxist approach rooted in unequal exchange between the rich countries of the Global North and poor countries of the Global South, which comprise 85% of the world’s population.