The 51-year-old was robbed and beaten in the attack on Tuesday afternoon near Connaught Place, New Delhi, a police spokesman said.
The woman managed to reach her hotel and the owner called police. No arrests have been made.
"When she came, it was miserable," said Amit Bahl, owner of the Amax Hotel. He said the woman was crying and "not in good shape".
"I am really ashamed that this happened," said Mr Bahl.
It is the latest case to focus international attention on rape and violence against women in India.
The problem has gained widespread attention since the gang rape and murder of a 23-year-old woman on a bus in December 2012. Public fury over the case has led to more stringent laws that doubled prison terms for rape to 20 years and criminalised voyeurism and stalking.
But for many women, particularly the poor, daily indignities and abuse continue and the new laws have not made the streets any safer. Ranjana Kumari, director of India's Centre for Social Research, said India's conservative, patriarchal traditions lead men to use rape as a tool to instil fear in women.
Experts say the rapid growth of India's cities and the yawning gulf between rich and poor are exacerbating the problem of sexual violence, with young men struggling to prove their traditional dominance in a changing world.
Cultural stigmas, police apathy and judicial incompetence have long made it difficult for women to even report rapes, but there has been a surge in the number of rapes being reported recently, suggesting women are emboldened to speak up.
Between January and October last year, 1,330 rapes were reported in Delhi and its suburbs, compared with 706 for all of 2012, according to government figures.
Last March, a Swiss woman who was cycling with her husband in central India was gang-raped.
These cases threaten India's lucrative tourism industry. Last year, the Tourism Ministry launched an "I Respect Women" campaign to reassure travellers.