Even "small improvements" would help reduce the risk of dying prematurely from cancer, the Australian researchers claimed.
Their findings, which also highlighted irresponsible sun tanning as a cause, were derived from an analysis of the country's cancer deaths.
Figures showed 44,000 Australians died from the umbrella of diseases in 2013 - of which 38 per cent were deemed preventable.
Obesity and infections were responsible for five per cent of the deaths while not exercising enough was blamed for 0.8 per cent.
Dr David Whiteman, lead researcher of the study published in the International Journal of Cancer, found that the bad habits fueled 41 per cent of cancer deaths in men and 34 per cent in women.
He said "this is because men smoke and drink more, spend more time in the sun and don't eat as well", ScienceAlert reports.
"While in many cases cancer is tragically unavoidable, this study highlights what we've known for years: cancer isn't always a matter of genetics or bad luck."
Dr Whiteman added: "There is a lot people can do to reduce their risk of developing and dying from cancer.
"Even small improvements in these areas would substantially reduce the number of people who die prematurely from cancer each year."
The new findings back up research earlier this year which revealed the remaining two thirds of cancer cases can be blamed on DNA errors.
The Johns Hopkins Kimmel Cancer Center study contradicted widespread belief that the disease is usually inherited or triggered by an unhealthy lifestyle.
Cancers triggered by copying errors could occur "no matter how perfect the environment", the researchers warned in March.
The findings explained why cancer can often strike people who follow all of the rules of healthy living and have no family history of the disease.
Tobacco and alcohol have long been at the centre of strict regulation due to their substantial links to cancer and heart disease.
And an emerging body of evidence has shown poor diets, not exercising enough and obesity are fueling rates of cancer.
What is responsible for cancer deaths
• Smoking - 20.3 per cent
• Poor diet - 5 per cent
• Boozing - 2.4 per cent
• UV radiation - 3.2 per cent
• Obesity - 5 per cent
• Infections - 5 per cent
• Not exercising - 0.8 per cent
• Hormones - 0.4 per cent