The 22-year-old, who underwent surgery at the hospital when she was 12 to correct her scoliosis, finished the cycle ride at Alexandra Palace on early Sunday morning.
The princess joined around 3,000 other fundraisers, including TV presenter Ben Fogle and actor Jim Carter.
She was raising the money for a £15 million (Rs 128 crore) appeal for the hospital’s development, as well as for the Marylebone Cricket Club.
Her sponsorship page says she has raised more than £9,000 (Rs 7.7 lakh) in total, including £500 (Rs 42,000) from her mother Sarah, the Duchess of York.
An accommodation unit at the hospital will be named Princess Eugenie House. The princess said that her experience of her procedure, in which two 12in rods were placed in her back, helped her to relate to other patients going through the same problems.