Farrells is an architecture and urban design firm founded by British architect and planner Sir Terry Farrell with offices in London, Manchester, Hong Kong, and Shanghai. The firm has won numerous awards for their characteristic mixed-use schemes, transit-oriented development, contextual urban placemaking, and cultural buildings.

Terry Farrell began his professional career in 1961 at the architecture department of the London County Council, where he met fellow staff architect Nicholas Grimshaw. The two became close friends, and in 1965 they founded the Farrell/Grimshaw Partnership, sharing their office for some time with Archigram. They were also part of a "new wave" of British firms experimenting with high-tech architecture. During this period Farrell/Grimshaw produced several pioneering works of high-tech, flexible buildings such as the 125 Park Road housing cooperative (1970) and the Herman Miller factory in Bath (1976); both of which have since been awarded Grade II listing by English Heritage. Grimshaw left the firm in 1980 to found Grimshaw Architects, while Farrell continued to work from their Paddington Street office.

The newly christened Terry Farrell and Partners married high-tech architecture to Farrell's growing interest in postmodernism, building conversion, and sensitive urban design. London was brimming with outmoded industrial buildings, which Farrell preferred to retain and repurpose rather than demolish. The firm completed numerous renovations characterised as "friendly adaptation of existing buildings". Both the TV-am and Limehouse Studios schemes transformed derelict industrial sheds into broadcasting studios. In 1987 the firm moved from the ex-Farrell/Grimshaw office into a Marylebone building formerly home to an aero-tyre factory, which they renovated to become the Hatton Street Studios.

Large-scale new build commissions in London such as Embankment Place (1990), Alban Gate (1992), and Vauxhall Cross (1994) cemented Farrell's status as Britain's "premier postmodernist". Farrell dismissed the term, insisting that his primary concerns are not about style, but rather urban space and a rejection of the "clean sweep" approach of traditional modernism.

Small-scale urban regeneration and conservation work, such as the Comyn Ching Triangle scheme (1982–1990), bolstered the firm's reputation for contextual urban design. The company conducted numerous master plans over the subsequent decades, including many in the London area. In East London, the firm was appointed to plan various projects in the Docklands and Thames Gateway regions. They have also developed revitalisation schemes for urban quarters including Regent's Place, Greenwich Peninsula, the Chelsea Waterfront, and Convoys Wharf. In 2010, the firm was appointed master planner for the long-term redevelopment of an area of Earl's Court surrounding the now-closed Earls Court Exhibition Centre. Terry Farrell rejected "big architecture" the site, stating: "I don’t think this masterplan is about the buildings. That’s starting at the wrong end of the process. Issues of height and density aren’t starting points. You have instead to talk about things like the street and its width and what makes a good city."

At the 2013 invitation of Ed Vaizey, the Minister for Culture, Communications and Creative Industries, Farrells commenced the Farrell Review of Architecture and the Built Environment meant to offer expert guidance on the direction of British architecture. The firm assembled a team of leading experts in architecture and urban design and conducted an extensive consultation process. In 2014 the Farrell Review report was published, providing 60 recommendations to government. The report was well-received and government moved to place design higher on the agenda, starting by shifting the ministerial oversight of architecture from the Department of Culture, Media and Sport to the Department for Communities and Local Government, and by forming a new parliamentary select committee on the built environment.

The Hong Kong office, incorporated as TFP Farrells, was founded in 1991. It was set up when the firm won an international competition to design the new Peak Tower, which opened in 1997 and was later featured on Hong Kong's $20 banknotes. The firm then won a competition to design the British Council/Consulate-General complex in Admiralty. This commission, announced by Margaret Thatcher in 1988, held significance as Britain's lasting presence in Hong Kong following the 1997 transfer of sovereignty over Hong Kong.

TFP Farrells developed a strong reputation in urban transportation infrastructure beginning with the design for Kowloon station (opened 1998) and the associated Union Square master plan, one of the largest air-rights developments on earth which includes the tallest tower in Hong Kong, the International Commerce Centre. The Ground Transportation Centre at Incheon International Airport, Seoul (2001) serves five different rail systems and won several awards. The firm subsequently won commissions to design additional MTR stations in Hong Kong (namely Tsuen Wan West, Kennedy Town, To Kwa Wan, Sung Wong Toi) in addition to railway stations in Johannesburg (three Gautrain stations) and Singapore (Punggol station). In recent years the firm has expanded into Mainland China, opening a Shanghai branch office and completing two of Asia's largest railway stations: Beijing South (2008) and Guangzhou South (2010).