Urubongse Rajasombhoj (Thai: อุรุพงศ์รัชสมโภช; RTGS: Uruphong Ratchasomphot; 15 October 1893 – 20 September 1909) was Prince of Siam (later Thailand).

His elder full sister, Princess Lavad Voraong, died in infancy.

Unlike the other princes, Urubongse was not educated in Europe, but instead received instruction from foreign teachers at a private residence in Siam.

His death brought sadness to the members of the Royal Family, especially King Chulalongkorn.

The king ordered the building of a bridge in the city with sculptures of Prince Urubongse set into both sides.