Early projects included the reconstruction and extension of the City and South London Railway (C&SLR), the building and extension of the Central London Railway, the construction of lifts beneath St Mary Woolnoth church at Bank tube station, the underpinning of Clifford's Tower, the reconstruction of Southwark Bridge and the widening of Blackfriars Bridge.

The company formed out of affairs relating directly to British infrastructure development in Egypt between 1890 and 1930, in particular MacDonald's involvement with Aswan Low Dam, starting in 1898.

In 1927, the two were later joined by PH East (also an engineer in the Egyptian government from 1907 to 1926) and Oswald Longstaff Prowde, at which time the name of the company was changed to Sir M MacDonald & Partners.

[15] In 2007, Mott MacDonald bought Dutch firm Euroconsult BMB who specialized in international development and natural resource management.

[20] In 2010, the firm added South African healthcare and development specialist HDA, and Australian engineering consultancy Hughes Trueman to its portfolio.

Mott MacDonald continued to expand its international presence in April 2013 with the purchase of Habtec Engenharia Ambiental,[22][23] a Brazil-based environmental consultancy with 80 people.

[24] In 2014, Mott MacDonald acquired AWT, a specialist water technology and consulting company based in New Zealand and Australia.

The move was a natural progression in the highly successful 15 year partnership between the companies through the joint venture Mott MacDonald Bentley.

It was the design engineer for Heathrow Terminal 5 sub-structures and foundations, as well as providing rail assurance services, tunnelling advice and project and program management.

[28] Mott MacDonald was the engineer and worked with Denton Corker Marshall on the design of the Manchester Civil Justice Centre which was completed in 2007.

[29] The Centre was designed and constructed to have minimal impact on the environment and included a narrow form, acoustic privacy, and natural ventilation.

[32] Mott MacDonald was chosen to be part of the design-build team for a $41 million bridge rehabilitation project announced by New York Governor Andrew Cuomo in January 2014.

[36] In January 2018, a Mott MacDonald employee distracted by a cell phone call left a tank unattended for an hour while working at the railroad's Albina Yard in Portland, Oregon, United States.

The former employee Robert LaRue Webb II was convicted with violating the Clean Water Act in October 2019 and was sentenced to a probation and a fine for negligently causing the oil release.