The more the women in the study practised yoga, the better their results were, researchers said.
Three months after the formal yoga practice had ended, results showed that on average, fatigue was 57 per cent lower in women who had practised yoga compared to the non-yoga group, and their inflammation was reduced by up to 20 per cent.
The participants had completed all breast cancer treatments before the start of the study and only yoga novices were recruited for the randomised, controlled clinical trial.
Participants practised yoga in small groups twice a week for 12 weeks.
"This showed that modest yoga practise over a period of several months could have substantial benefits for breast cancer survivors," said Janice Kiecolt-Glaser, from The Ohio State University and lead author of the study.
"We also think the results could easily generalise to other groups of people who have issues with fatigue and inflammation," said Kiecolt-Glaser.
Though many studies have suggested that yoga has numerous benefits, this is the largest known randomised controlled trial that includes biological measures, Kiecolt-Glaser said.
The study is published in the Journal of Clinical Oncology.
The research team focused on breast cancer survivors because the rigours of treatment can be so taxing on patients.
"One of the problems they face is a real reduction in cardiorespiratory fitness. The treatment is so debilitating and they are so tired, and the less you do physically, the less you're able to do. It's a downward spiral," she said.
"That's one reason we think there are higher levels of inflammation in cancer survivors, meaning that an intervention that reduces inflammation could potentially be very beneficial," said Kiecolt-Glaser.