Devolution is the transfer of power, responsibilities, and resources from the national government to the county governments and is provided for in the Constitution of Kenya, 2010 chapter 11.
The question on whether Devolution under the Constitution of Kenya 2010 is a success or a challenge to national unity depends on how well its implementation is managed. However, Devolution has strengthened national unity in different ways which are now termed as success and on the other hand it has also introduced new challenges.
Ways in which Devolution is a success in promoting national unity:

i.Devolution has played a very key role in promoting equity and Inclusivity.
Article 174 (e) provides that the objects of devolution is to protect and promote the interests and rights of minorities and marginalized communities. This has greatly reduced inequalities and isolation fostering a sense of belonging and national unity.

ii. Devolution has established a new regime of accountability in which national and county governments are able to exercise checks and balancing on each other. This enhances democratic government and reduces abuse of power at the national level.

iii. Local Participation has been increased where Article 174(c) gives the people powers of self-governance and increase the people's participation in the exercise of the powers of the State. This has increased democratic culture and patriotism.

iv. Article 6(2) and Article 174 (g) emphasize on decentralization of state organs and services. This has played a very key role in promoting national unity where all regions now feel included in the country’s governance.

Devolution has been challenging in advancing national unity in the following ways:
i.Corruption and Mismanagement.
Article 10(2)(c) promotes good governance, integrity, transparency, and accountability. This maybe a challenge where many county governments have been involved in corruption, misuse of funds, and lack of accountability resulting to decline of public trust in the devolved units.

ii.Inter-Governmental Conflict.
Power struggles and lack of clarity in roles have led to disputes over functions. This tension can be a challenge to good governance and can as well threaten unity.

iii.Increased conflicts in relation to resource allocation.
Devolution has sometimes increased competition for resources such as land, water, and revenue among counties or communities, leading to border disputes and even violence.

iv.Ethnic and Clan-Based Politics.
Some counties have experienced ethnic favoritism, where leaders allocate jobs and resources to their ethnic or clan groups. This causes local marginalization, exclusion, and inter-community conflicts.

In conclusion, Devolution can make Kenya's national unity even stronger if its principles are adhered to the letter as stipulated in the Constitution of Kenya, 2010.