Phra Chao Lan Thoe Phra Ong Chao Sirivannavari Nariratana (; RTGS: —Siriwannawari Narirat; Literally: "Princess Sirivannavari Nariratana, the Royal Granddaughter"), or Princess Sirivannavari Nariratana (8 January 1987—present) is a princess of Thailand and the only daughter of Crown Prince Maha Vajralongkorn and Mom Sujarinee Mahidol (Vivacharawongse), who is commonly known as Yuvadhida Polpraserth.

She was born Mom Chao Busyanambejira Mahidol (; RTGS: ฺีButnamphet Mahidon), but later changed to Mom Chao Chakkrityapha Mahidol (), and once again to Mom Chao Sirivannavari Mahidol upon order of Queen Sirikit.

She has four siblings as follows:

• Mom Chao Juthavachara Mahidol (August 29, 1979—present)

• Mom Chao Vacharaesorn Mahidol (May 27, 1981—present)

• Mom Chao Chakriwat Mahidol (February 26, 1983—present)

• Mom Chao Vatcharawee Mahidol (June 14, 1985—present)

After the divorce of her mother, she moved to United Kingdom with her mother and siblings. However, she later was taken by her father from England and brought back to Thailand.

She was later elevated to Princess Sirivannavari Nariratana by the royal command of her grandfather, King Bhumibol Adulyadej, on June 15, 2005.

In 2009, she was ranked 5th hottest young royals in the world by Forbes Magazine.

Education

Princess Sirivannavari received her primary and secondary education at Chitralada School. She currently studies fashion and textile in the Faculty of Fine and Applied Art, Chulalongkorn University.

Personal life

Princess Sirivannavari has many interests in the field of arts and sports. The princess has represented Thailand in badminton at 23rd SEA Games in the Philippines, following the footstep of her grandfather, King Bhumibol Adulyadej, who has represented the country in international sporting events, although she did not win any medals from the 2005 Southeast Asian Games.

In 2007, she was invited by Pierre Balmain, the French couturier, to present her fashion show in Paris. Her debut Paris collection was Presence of the Past, which drew on memories of her grandmother as well as giving a modern twist to Thai traditional costume . She recently presented her own fashion show at Paris Fashion Week : Spring/Summer 2008.

In 2008 she was included as 16th on the list of the "20 Hottest Young Royals" as compiled by Forbe's Magazine.
thumb|right|230px|Royal cypher of Princess Sirivannavari