Samuel Barton Worthington was articled to Joseph Locke in 1836 to work first on the construction of the Grand Junction Railway. He worked with Locke on many of the surveys of English and Scottish railways on which Locke was engaged, including the Glasgow-Greenock Railway, the Lancaster & Preston Junction railway, and the Sheffield & Manchester Railway. Between 1840 and 1844 he was in France with Locke working on the construction of the Paris to Rouen Railway. In 1844 he returned to England to be resident engineer for the southern half of the Lancaster & Carlisle Railway. When the line opened in 1846 he became engineer to the company. The Lancaster & Preston Junction Railway was placed under his charge in 1850. In 1859 the Lancaster & Carlisle was leased to the London & North Western Railway and Worthington was placed in charge of the lines from Carlisle to the Liverpool and Manchester line. In 1862 his division was extended to include all lines north of Crewe except the Cromford & High Peak Railway, and he remained Engineer of the London & North Western Railway Northern Division until his retirement in 1886. He practised as a consulting engineer from then until 1896. He was a Member of the Institute of Civil Engineers (1861) and the Institute of Mechanical Engineers (1860).

After four years at Owen's College at London University, William Barton Worthington was articled to his father, S. B. Worthington, who was then Engineer of the Northern Division of the London & North Western Railway. He then spent a year on the Carlisle Joint Station reconstruction works and a year as an assistant to Messrs. Blyth and Cunningham of Edinburgh on the Caledonian Railway works. In 1878 he was apprenticed resident engineer for the London & North Western Railway on new works in and around Manchester. He became an assistant to S. B. Worthington in 1883, and in 1886 was appointed Engineer of the Lancashire Division of the London & North Western Railway. In 1890 he became Assistant Engineer of the Lancashire & Yorkshire Railway, and was appointed Chief Engineer to the company seven years later. In 1905 he was appointed Chief Engineer of the Midland Railway. After his retirement in 1915, he practised as a consulting civil engineer in London. W. B. Worthington was elected President of the Institute of Civil Engineers in 1917 but was prevented by illness from taking up office. He was able to serve as President in 1921-2 and then served on the Council until November 1927. In 1923 he received an honorary degree of D.Sc. from Manchester University. He was also Chairman of the Engineering Joint Council in 1922-3, President of the Smeatonian Society of Civil Engineers in 1928, and a Member of the Institute of Mechanical Engineers (1897).