After completing his PhD, Bullard moved to Texas to teach at Texas Southern University where he met his future wife, Linda. In 1979, Linda represented Margaret Bean and other Houston residents as they struggled against a plan that would locate a district landfill site next to their homes. The middle-class Northwood Manor neighbourhood was an unlikely location for municipal garbage disposal – except for the fact that the vast majority of the neighbourhood's citizens were black. The lawsuit was ground-breaking in that it was the first to charge environmental discrimination in waste facility siting under federal civil rights laws. Bullard was drawn into the case as an expert witness; Linda asked him to conduct a study documenting the location of Houston's landfill sites. Alongside his research team, Bullard identified that African American neighbourhoods in Houston were the premier choice for toxic waste sites; all five of the city's garbage dumps, six of the city's eight garbage incinerators and three of the four privately owned landfill sites were located in black neighbourhoods, although black people made up only 25% of the city's population. This was the first comprehensive account of environmental racism in US history.

These discoveries lead Bullard to pursue an academic career focusing on environmental justice and a life of campaigning against environmental racism. "Without a doubt", Bullard would later say, "it was a form of apartheid where whites were making decisions and black people and brown people and people of colour, including Native Americans on reservations, had no seat at the table."

Also in 1990, Bullard joined an influential group of academics known as the Michigan Group that wrote to the Secretary of the US Department of Health and Human Services and the head of the Environmental Protection Agency asking for meetings to discuss government policy on environmental discrimination. The Secretary ignored their inquiries, but William Reilly, then head of the EPA, responded and met with the group several times. These meetings would result in the creation of the EPA's Work Group on Environmental Equity (known today as the Office of Environmental Justice) which provides technical and financial assistance to communities working to address issues of environmental justice.

Bullard also played an integral part in forming the 1991 National People of Color Environmental Leadership Summit, the first conference of its kind where over 300 minority-led environmental groups (up from just 30 thanks to Bullard's dedicated networking) came together to discuss issues of environmental justice. Together, these groups created and adopted a list of seventeen "Principles of Environmental Justice" that proclaimed their shared values and goals. This first summit would later be described as one of the most important events in the history of the environmental justice movement. A few years later, Bullard chaired the Health and Research subcommittee of the newly-founded National Environmental Justice Advisory Council, a federal advisory committee to the EPA that provides recommendations about broad issues relating to environmental justice and integrating environmental justice with other EPA initiatives. His research and expertise as part of the committee played a critical role in persuading President Bill Clinton to sign Executive Order 12898, the first legal document that defined the need for environmental justice in the United States.

His work has continued in the years since, both chronicling contemporary environmental justice activism (he now has 18 award-winning books to his name) and playing an active role in promoting community-led grassroots campaigns himself. His academic work has inspired a new generation of environmental justice researchers; he is currently both Distinguished Professor of Urban Planning and Environmental Policy and Director of the Bullard Center for Environmental and Climate Justice at Texas Southern University. Alongside Dr Beverly Wright, Bullard founded the Historically Black College and University Climate Change Consortium, an association of higher education institutions that raises awareness of the disproportionate impact of climate change on marginalised communities in order to develop student leaders, scientists and advocates on issues related to environmental and climate justice policies. Just last year, Bullard was awarded the United Nations Environment Program's Champions of the Earth Lifetime Achievement Award, the UN's highest environmental honour, in recognition of his efforts to champion a different, fairer way of protecting the environment. When asked what keeps him fighting for environmental justice, Bullard replied "People who fight... People who do not let the garbage trucks and the landfills and the petrochemical plants roll over them. These companies have been put on notice that they can't do this anymore, anywhere."