A study published in The Lancet Planetary Health journal found policies to that end could, each year, save 5.86 million lives due to better diets, 1.18 million lives from cleaner air and 1.15 million lives through more walking and cycling by 2040.
In 2015, governments set a global goal of limiting average temperature rise to "well below" 2 degrees Celsius above preindustrial times and set emissions reduction targets as a first step to getting there.
On Monday, however, UN Secretary-General Antonio Guterres urged countries to take bolder action ahead of November's COP26 UN climate conference and come up with stronger 2030 targets consistent with cutting emissions to net zero by 2050.
The new research highlighted how the potential health benefits of climate action could give added impetus to countries to submit more ambitious national climate plans ahead of COP26.
The nine countries modelled in the study - the United States, China, Brazil, Germany, India, Indonesia, Nigeria, South Africa and Britain - represent half of the world's population and 70% of global emissions.
Six of them have yet to submit revised climate action plans, which were due in 2020 but put back by many countries as the COVID-19 pandemic delayed the climate summit for a year.
"Ahead of COP26, we'd like to see governments focus on health as one of the priorities in climate change policies," said lead author Ian Hamilton, executive director of The Lancet Countdown on Health and Climate Change.
"There's good evidence to show that meeting the Paris Agreement commitments will be good for our health, and that these benefits accumulate to those individuals in the countries taking leadership," he told the Thomson Reuters Foundation.
Using national and international data, the study analysed emissions generated by the energy, agriculture and transport sectors, along with factors like national diets and lifestyles.
The researchers modelled the scenarios required for each country to meet the Paris accord, including changes like adopting cleaner energy and reducing car use, as well as to achieve global development goals such as zero hunger.
They found that changes towards "flexitarian" diets - with moderate amounts of animal-based foods and a high share of plant-based foods - offered the greatest health benefits as well as reducing carbon emissions.
For example, many deaths would be avoided by lower rates of non-communicable diseases such as obesity and heart disease, connected to excessive consumption of carbon-intensive red meat and processed foods, and lack of access to fruit and vegetables.
"Why wouldn't we prioritise investments that will save more lives near-term if they give us the same amount of carbon value?" said Aaron Bernstein, interim director of The Center for Climate, Health, and the Global Environment at the Harvard TH Chan School of Public Health.
Changing diets is a complex challenge for governments, he noted, but potential ways to do it include subsidising healthier foods and putting a price on the emissions produced by more carbon-intensive foods that require a lot of natural resources.
Beef production, for instance, fuels greenhouse gas emissions as carbon-storing forests are cut down for pasture and cattle burp out methane.
A focus on health is one way to make climate action more personal and appealing, Bernstein added, instead of being framed as a cost now that will bring benefits for future generations.
"We have to make this issue relevant to today, and (talk about) improving the welfare, economic opportunities and health of people in a time frame that they can get their heads around," he said.
A separate study out on Tuesday found pollution from burning fossil fuels causes one in five premature deaths globally, totalling 8.7 million in 2018 and suggesting the health impacts of those emissions may be far higher than previously thought.