The research, from Harvard Medical School, is the largest prospective study to date on ejaculation frequency and prostate cancer.
The study followed almost 32,000 healthy men for 18 years, 3839 of whom were later diagnosed with prostate cancer.
The researchers asked the male volunteers about their average monthly frequency of ejaculation between the ages of 20-29 and 40-49.
They found that frequency of orgasm throughout both periods did have an impact on the risk of prostate cancer.
For instance, men who ejaculated 21 or more times per month between the ages of 40-49 had a 22% reduction in risk of developing prostate cancer compared to men who ejaculated four to seven times per month.
However, the reason behind this link is still unknown.
"While these data are the most compelling to date on the potential benefit of ejaculation on prostate cancer development, they are observational data and should be interpreted somewhat cautiously," Dr Jennifer Rider of Harvard Medical School said in a statement.
"At the same time, given the lack of modifiable risk factors for prostate cancer, the results of this study are particularly encouraging."
The research was presented at the American Urological Society earlier this week.
This isn't the first study to link a man's bedroom habits to his prostate cancer risk.
A 2014 study found that men who'd had sex with more than 20 female partners were 28% less likely to develop the disease than those who'd only slept with one partner in their lives.
The researchers also found that men who had never had sex were nearly twice as likely to develop prostate cancer as those who had.
Commenting at the time, co-author of the study Professor Marie-Elise Parent said: "It is possible that having many female sexual partners results in a higher frequency of ejaculations, whose protective effect against prostate cancer has been previously observed in cohort studies."