Ms Tulsi, 31, was administered the oath of office by the John Boehner, Speaker of the House of Representatives.
"I chose to take the oath of office with my personal copy of the Bhagavad-Gita because its teachings have inspired me to strive to be a servant-leader, dedicating my life in the service of others and to my country," Ms Gabbard said after the swearing in ceremony on Thursday.
"My Gita has been a tremendous source of inner peace and strength through many tough challenges in life, including being in the midst of death and turmoil while serving our country in the Middle East," she said explaining the reasons for taking the oath of office on Gita.
"I was raised in a multi-racial, multi-cultural, multi-faith family. My mother is Hindu; my father is a
Catholic lector in his church who also practices mantra meditation. I began to grapple with questions of spirituality as a teenager," Ms Gabbard said.
"Over time, I came to believe that, at its essence, religion gives us a deeper purpose in life than just living
for ourselves. Since I was a teenager, I have embraced this spiritual journey through the teachings of the Bhagavad-Gita.
"..In so doing, have been blessed with the motivation and strength to dedicate my life in service others in a variety of ways," she said.
Proud of her Hindu religion, she is not Indian or of Indian heritage. Her father Mike Gabbard is currently Hawaii State Senator and mother Carol Porter Gabbard is an educator and business owner.
At 21, she became the youngest person to be elected to the Hawaii Legislature. At 23, she was the state's first elected official to voluntarily resign to go to war. At 28, she was the first woman to be presented with an award by the Kuwait Army National Guard.