The 12 km (7.5 mi) long road runs along the bend of Chao Phraya River on the Phra Nakhon side (Bangkok core).
Rama III Road starts from the foot of Krungthep Bridge in Thanon Tok quarter where it intersects with Mahai Sawan and the last phase of Charoen Krung Roads in the area of Bang Kho Laem District.
It then runs eastward up till Nang Linchi Junction, where it crosses Nang Linchi Road in front of Wat Chong Lom temple, and then northeastward across Chuea Phloeng Road and Eastern Railway Line (Mae Nam Branch) from nearby Mae Nam Railway Station on the periphery of Yannawa and Khlong Toei Districts, and then enters Khlong Toei area.
Many businessmen and investors built high-rise buildings and port warehouses along the road, such as CentralPlaza Rama III, Bank of Ayudhya Headquarters, Bangkok Bank, Rama III Office and IT Division.
It was named in honour of Nangklao (Rama III), the third sovereign of Chakri dynasty, who was regarded as an expert in merchanting, to match the road history and its condition.