With family and some other support Doherty qualified as a teacher for both primary and secondary schools, mainly in the Catholic system. His university degree was achieved through correspondence while working as a full-time teacher.
He was radicalised by experiences in Innisfail (Queensland) where Aborigines were harshly treated and sugar workers often treated with contempt. Many of the parents annoyed by his growing critical attitudes pointed to his red hair and said “you ought to be a communist!”.
A few years later, involvement in “Right to March” campaigns against Joh Bjelke Petersen in Brisbane and then a time with the Alice Spring Peace Group marked a real turning point in his life that led him to the Communist Party of Australia. He joined the CPA in 1989.
Denis Doherty has lived in the inner west suburb of Glebe for over 20 years. He is well known as the former chair of the Glebe Youth Centre and former chair of the Glebe Neighbourhood Centre and for his work in campaigns including prison reform and against overdevelopment.
Doherty is best known for his long commitment to peace and to ridding the world of nuclear weapons. He was a founding member of the Australian Anti-Bases Campaign Coalition and has been the national coordinator of the campaign for over 20 years. He was selected to receive a community peace prize by the Sydney Peace Foundation at the University of Sydney.
People from all around New Zealand converged on the super-secret Waihopai satellite interception spy base, near Blenheim, on the weekend of January 24-26, 2003, for an anti-war protest. The New Zealand Anti-Bases Campaign, which organized the protest, points out that as the world stands on the brink of being sucked into an aggressive American-led war on Iraq, Waihopai is New Zealand's most important contribution to the American war machine.
The Waihopai protest was joined by representatives from the Australian Anti-Bases Campaign Coalition, Denis Doherty and Hannah Middleton. In October 2002 the AABCC organized a major protest at the huge US spy base at Pine Gap (near Alice Springs), which is serviced through the US military base at Christchurch Airport.
In February 2009 Communist Party of Australia elected a new leadership after the death of long time General Secretary Peter Symon. The Party for the first time elected a woman to the position of Party General Secretary, well known political activist and former Party President Dr. Hannah Middleton.
Dr. Middleton was elected unanimously to the Party’s highest leadership position. Guatemalan born West Australian trade unionist Vinnie Molina was elected as the CPA’s new National President. For the first time in two decades the Party elected a National Organiser Denis Doherty.
- Denis Doherty of the Port Jackson Branch in Sydney made a number of points about his work in the peace movement, including the need for the CPA to increase the impact of its message about the $60 million a day cost of the Australian military. Denis was one of a group of about 70 activists who journeyed to Rockhampton in June to confront the huge joint Australian-US military exercise called "Talisman Sabre".
- Denis pointed to the huge drain the $60 million a day makes on the well being of the community.
- "In the Australian education system there are 3.2 million students, 250,000 teachers and 90,000 schools. Yet the Australian military attracts more funding than Education. The military have less than 10,000 members, but their equipment is extremely and exorbitantly expensive."
On October 22, 2011, Lindy Nolan, Drew Cottle and the Communist Party of Australia's Denis Doherty, addressed an event at the CPA's office in Surry Hills, Sydney, celebrating the 50th anniversary of the defeat of the referendum to ban the Communist Party of Australia.
"Hands off Glebe"
A well attended public meeting held in Glebe (Sydney) on February 1, 2012, heard details of the state government’s plans to privatise much of public housing land at Cowper Street in this inner city suburb. The meeting was unanimous that the government has to reinstate public housing on the site.
Denis Doherty addressing the public meeting in Glebe regarding the Cowper Street development.
The Communist Party of Australia Port Jackson Branch has been involved with Hands off Glebe since the 2010 federal election and has been campaigning with them to save and extend public housing in Glebe.
Sydney Hiroshima Day March & Rally 2012 Sunday, 5 August 2012, Hyde Park North, Sydney
- Colonel Valery Yarynich – retired Russian Colonel
- MP Jamie Parker – NSW Greens uranium spokesperson
- Rita Mallia – NSW President, Construction Forestry Mining Energy Union
- Denis Doherty – Anti Bases Campaign
- Chair: Radhika Raju (CFMEU) &
- Miko Nakamura (311 campaign for nuclear free) 
In 2012 the local council areas of Auburn and the City of Sydney featured Communist Party of Australia members running as candidates. In Auburn, running for the Battler was Tony Oldfield, a well-known local activist and party member. In the City of Sydney was Denis Doherty running as Mayoral and Councillor Candidate with the Housing Action Team.
Denis Doherty is part of a "historic shift" in left politics in Sydney where the team of which he is the lead member is composed of Socialist Alliance members and other community members. The Housing Action Team has Ray Jackson from the Indigenous community, Raul Bassi an Argentinian migrant and now activist, Jay Fletcher journalist with Green Left Weekly and Andrew Chuter a maths teacher from Erskinville.
- CPA Guardian Issue #1467, 11 August 2010. Meet the CA candidates
- The Guardian February 5, 2003, Waihopai spy base protest by Dr Hannah Middleton
- CPA South Australia Blog. Monday, February 23, 2009 Communist Party elects new General Secretary
- [ http://onwww.cpa.org.au/z-archive/g2005/1249congress_dels.html The Guardian 19 October, 2005 CPA 10th Congress: delegates have their say]
- The Guardian, Issue #1534 8 February 2012
- Guardian Australia July 25 2012
- The Guardian, Issue #1559 8 August 2012