She was 90.
Once listed among the 'World's Ten Most Beautiful Women' by Vogue magazine and a style icon during her time, Devi was the founder of the Swatantra Party and a member of the third and fourth Lok Sabha.
She was admitted to Satokben Durlabh Memorial Hospital early this month and was discharged a few days ago but was readmitted yesterday for chest infection.
"She recovered from her gastrointestinal problems but yesterday she was detected with a lung infection. Her condition deteriorated this morning and she succumbed to her illness," Dr Subhash Kala, who was attending on her, said.
The London-born princess of Cooch Behar was the third Maharani of Jaipur from 1939 to 1970 after her marriage to Maharaja Sawai Man Singh II and was later known as Rajmata or Queen Mother.
She entered active politics on an anti-Congress plank in 1962 when she founded the Swatantra Party in Rajasthan. She won a landslide victory from Jaipur Lok Sabha seat in 1962 and again emerged victorious in 1971. She was lodged in Tihar Jail in Delhi during Emergency.
The elegant Gayatri Devi's death comes a day after the passing away of actress Leela Naidu, both of whom were named by Vogue as amongst the 10 most beautiful women in the world.
After serving five months in the Delhi Jail for allegedly breaking tax laws, she retired from politics.
Gayatri Devi studied at Shantiniketan and later in Switzerland before marrying in 1940 into the Jaipur royal family.
Her son Prince Jagat Singh died in 1997 and she is survived by her two grand children Rajkumari Lalitya Kumari and Dev Raj Singh.
She was the founder of two well known schools of Jaipur- Maharani Gayatri Devi (MGD) Girls School and Sawai Man Singh (SMS) Vidhyalaya.