In 1873 Thomas Millard bequeathed £8000 to Trinity College for the advancement of mathematical and natural science; the College spent part of this donation on the Millard Engineering Laboratory which was erected in 1886. This Laboratory was the only facility available to the first Professor of Engineering Science, Charles Frewen Jenkin, who was appointed in 1908. In 1910 Engineering Science was established as a final honour school within the Faculty of Natural Science. In the same year an electrical laboratory, housed in Keble Road, was added to the Department's facilities and in 1914 new accommodation for the Department was built at 19 Parks Road which was named the Jenkin Building in 1983.

The Department steadily grew until the 1950s when it experienced a period of great expansion under the headship of Professor Thom. During the 1950s there was a rise in Governmental pressure for an increase in training of engineers; this, combined with a belief in the University that the Engineering Department was too small, led to the establishment of the Committee on the Future of Engineering Science which comprised members from Cambridge University (which had a large and successful engineering school), industry and Oxford University. The committee recommended that the number of undergraduates admitted be doubled and highlighted the need for more space for the Department. As a result of the recommendations, a new engineering building was built, the Thom Building, which was opened in 1963. A new joint honour school in Engineering Science and Economics (ESE) was established in the same year and ran until 1989.

In 1967 the department began teaching a diploma in The Science and Application of Electric Plasmas which became an MSc in 1972; this course was discontinued in 2002. Expansion of the physical size of the department continued with the purchase of the old power station in Osney in 1971 (this was later named the Southwell Laboratory) and the erection in 1976 of a building shared with Metallurgy which was given the name of the Holder Building in the early 1980s.

After the sudden death of the head of the Department (Professor Holder) in 1977, the Department went through a phase of further expansion and change. Firstly, the headship of the Department became a rotating office. There were several professors who worked on differing fields of engineering in the Department at this time and it was decided that the appointment should not be restricted to one subject; a term of 5 years as head was agreed on. A joint honour school in Engineering, Economics and Management (EEM) began in 1979 followed in 1986 by two four-year courses in Engineering and Computer Science (ECS) and Electronic and Structural Materials Engineering (ESME). The development of ECS and ESME and the change of Engineering Science (ES) into a four-year course were developed partly as a result of expansion under the Government's Engineering and Technology programme which encouraged an increase in the teaching of Engineering in universities.

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