The Robert Stephenson & Company, at Forth Street, Newcastle-upon-Tyne, became the world's first locomotive builder. To gain further experience, Robert went to Columbia in South America in 1824 where he worked at gold and silver mines. While in Columbia Robert Stephenson met the inventor, Richard Trevithick, and provided the funds that he needed to get back to Britain. After three years in South America, Stephenson was recalled to England and began work on the Rocket locomotive. Robert's abilities as an engineer was illustrated by the success of the Rocket at the Rainhill Trials in October, 1829. During this period Robert and George Stephenson were kept busy producing locomotives for the Bolton & Leigh Railway and the Liverpool & Manchester Railway. This included locomotives such as the Northumbrian and the Lancashire Witch. In 1833 Robert Stephenson was appointed chief engineer of the London & Birmingham line. This was the first railway into London and involved solving difficult engineering problems such as the Blisworth Cutting and the Kilsby Tunnel. The London & Birmingham line was completed in 1838.

For the next few years Stephenson was involved in constructing railways all over the world. He also built bridges, including those that crossed the Tyne at Newcastle and the Menai Straits. The Britannia Bridge at Conway was made up of two huge, rectangular, wrought iron tubes. Stephenson constructed a similar bridge over the St. Lawrence at Montreal, Canada (1854-59). For many years, this was the longest bridge in the world. In the 1847 General Election Stephenson was elected as the Conservative MP for Whitby. Stephenson did not take an active role in the House of Commons and usually only contributed to debates on engineering issues. Stephenson never enjoyed good health and early in 1859 he was advised to retire from business and politics. He took a yachting cruise but when he arrived in Norway his condition deteriorated and he was rushed back to England. Robert Stephenson died on 12th October, 1859.