The Capital Centre of Kenya, Nairobi Central Business District/EZEKIEL AMING'ANairobi contributes more than a quarter of Kenya’s economic output, while Wajir, Mandera and Turkana remain at the bottom of the county economic rankings.
The new report highlights deep disparities in wealth, infrastructure and business opportunities across the country.
The findings are contained in the 2026 County Development Index (CDI) report, which ranks Nairobi as the country’s strongest county economy, followed by Kiambu, Nakuru and Mombasa.
Nairobi scored 0.96, with a Gross County Product (GCP) estimated at more than Sh4.1 trillion, accounting for 27.5 per cent of Kenya’s gross domestic product.
Kiambu ranked second with a score of 0.89 and an economy valued at Sh819.8 billion. Nakuru followed with 0.87 and Sh771.8 billion, while Mombasa scored 0.84 with an estimated GCP of Sh711 billion.
Nyeri completed the top five with a score of 0.81 and an economy valued at Sh265 billion.
The report attributes the strong performance of leading counties to diversified economic activities, infrastructure, private investment and employment opportunities.
Kiambu and Nakuru benefit from their proximity to Nairobi, strong manufacturing sectors and commercial activities.
Mombasa’s performance is supported by its position as Kenya’s main port city, with manufacturing and services accounting for about 75 per cent of its economic output.
“The top counties benefit from relatively diversified economic structures supported by manufacturing, commercial agriculture, logistics, wholesale and retail trade, education, tourism and professional services,” the report states.
The index assesses more than the size of county economies. It considers eight indicators, including economic output, contribution to national GDP, labour force participation, youth unemployment, economic diversification, poverty levels, multidimensional poverty and the business environment.
Other strong performers include Meru, which scored 0.77, and Machakos, Murang’a and Uasin Gishu, which each recorded 0.76.
At the bottom of the rankings, Wajir scored 0.07, Mandera 0.09 and Turkana 0.12. Samburu and Marsabit followed with scores of 0.15 and 0.16, respectively.
Garissa scored 0.18, while West Pokot recorded 0.25.
The report links the weak performance of these counties to limited industrial activity, low investment, dependence on livestock production, poverty and underdeveloped private sectors.
“Their low output reflects relatively small populations, limited industrial activity, low investment levels, dependence on livestock production and weak private sector development,” the report says.
The study, conducted by the SDG Kenya Forum with support from the Gates Foundation, argues that economic performance shapes employment, household incomes, poverty reduction and the quality of life.
It recommends that counties develop economic diversification strategies based on their local strengths while strengthening agricultural value chains, agro-processing and manufacturing in productive rural areas.
The report also calls for improved investment promotion and business systems to attract private capital, particularly in counties with limited economic opportunities.
Economist Samuel Kimote said infrastructure, human capital and institutional capacity were among the factors separating high-performing counties from those struggling economically.
“The strongest-performing counties benefit from a combination of economic opportunities, infrastructure, human capital, institutional capacity and better service systems,” he said.
The report warns that counties with weak infrastructure often struggle to expand economic activity, generate revenue and invest in public services.
Separately, its fiscal management rankings placed Narok first, with a score of 0.79, supported by strong revenue collection and budget execution.
Mombasa ranked second at 0.69, followed by Nyeri at 0.68. Nyamira recorded the weakest fiscal management performance, scoring 0.16, with the report citing a high wage bill, low budget execution and limited revenue collection.
