Top 10 IT Services Companies in the UK

Top 10 IT Services Companies in the UK: Leaders Adapt to the AI Era

London, June 29, 2026 – UK businesses and public sector organizations are making new demands on their IT services partners, and this is being reflected in industry analyst firm PAC’s latest view of the £50bn sector.

PAC has published its latest ranking of the top ten IT services providers based on UK revenue, and while overall market conditions remain challenging, the largest vendors out-paced overall market growth.

Total spending on IT services by UK organizations increased by only 2.2% in 2025, but more than half of the top ten players were able to beat this level of growth as clients turned to larger players to support their evolving needs. As appetite for artificial intelligence continues to increase, clients are looking to work with vendors that can accelerate their adoption of AI at scale, and want to work with partners that are adapting their skills, offerings and engagement models to help them transform at speed.

More details for our SITSI customer > “IT Services – Preliminary Vendor Rankings – UK“

Part of the journey to harnessing AI effectively is migrating legacy applications and workloads to more robust platforms, and ERP modernization and legacy transformation remain an important aspect of many of the largest IT services deals signed in the UK in recent months. This also plays to the strengths of the larger vendors that have the depth of resources to manage this transition at scale.

TCS once again topped the rankings as the largest IT services supplier in the UK, and reinforced its position through new wins with clients including NHS Supply Chain and Aviva, as well as extending its relationships with customers including Kingfisher and Virgin Atlantic. The company’s successful expansion into the public sector has been a key part of its recent development and it recently committed to creating 5,000 new jobs in the UK during the next three years.

Accenture ranked in second place, and made the most eye-catching acquisition in the UK market last year with the purchase of Faculty AI, which develops the “Frontier” data intelligence platform. This move highlighted the new types of investment that IT services providers are increasingly making as they build more AI-centric and platform-based propositions to drive differentiation and speed time-to-value.

Capgemini and IBM both enjoyed strong years in the UK, with each posting double-digit rises in revenue as a result of both organic and inorganic growth. Capgemini is leading complex, transformation projects at organizations such as HMRC and National Grid that aim to help them unlock the value in their huge and escalating data volumes. IBM’s long-term investments in AI, cloud and cyber security are starting to pay dividends as it helps UK organizations such as the Home Office and the Ministry of Defence (MoD) build the digital foundations to support their future strategies. 

The fastest growing of the top ten players was CGI, due in part to the integration of its acquisition of domestic IT services challenger BJSS, but also to a string of major wins in the commercial, defence and central government sectors. PAC expects the public sector to be the UK’s fastest-growing IT services market for the next five years, as long-term transformation cycles in the NHS and the MoD drive a more data- and AI-centric approach.

Nick Mayes, Principal Analyst at PAC, said: “While the leading players in the UK IT services market have remained fairly consistent for several years, there are a lot of changes happening beneath the surface. All IT services suppliers need to adapt fast as AI shakes up and cannibalizes the delivery and commercial models that have underpinned this sector for decades. If we were to fast-forward a further five years, the leading players will be those that have most successfully pivoted around these fundamental shifts.”

Despite the current economic headwinds, PAC expects UK spending on IT services to accelerate to growth of just over 3% in 2026. Legacy transformation will be the primary contributor to project volumes, but aspects such as cyber resilience, data sovereignty and cloud platform optimization will also create new growth opportunities for suppliers. These areas will be a key focus for PAC’s research agenda in the coming months.

About PAC

We are a data-driven market research firm with a consulting DNA. Since 1976, PAC has been providing targeted and objective solutions to the growth challenges faced by software and IT service providers worldwide. We are their preferred partner for defining strategy, strengthening market share, optimizing go-to-market approaches, and helping them position themselves as thought leaders. PAC is an analyst firm with a team of over 50 employees and offices in four European countries. We conduct market research across more than 30 countries through our “Research, Consulting, and Visibility” pillars and our renowned SITSI® research platform.