This study used a systematic review methodology. The systematic review method was adopted to provide transparency, replicability, and rigor in finding, choosing, and examining the literature ([20]). The review adhered to the established principles for systematic reviews in the social sciences, taking cues from the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework ([34]).

A comprehensive search of relevant literature was carried out using electronic databases such Web of Science and Scopus. The databases were chosen because of their large-scale coverage of top-tier journals which have been peer-reviewed and published in social sciences and related fields ([35]; [36]).

The search strategy consisted of predefined keywords and Boolean operators that were relevant to the study objectives. The search strings were changed according to the syntax of each database so that the best retrieval would be achieved. The search was restricted to journal articles to guarantee academic quality and uniformity. Scopus was searched with the following search terms, “TITLE-ABS-KEY (governance OR "public administration" OR "public sector reform" OR "institutional reform" OR "policy reform" OR "anti-corruption" OR decentralization OR "institutional drivers") AND TITLE-ABS-KEY (Nigeria OR Nigerian) AND PUBYEAR > 1998 AND PUBYEAR < 2026”, and Web of Science using, “TS = (governance OR "public administration" OR "public sector reform" OR "institutional reform" OR "policy reform" OR "anti-corruption" OR decentralization OR "institutional drivers") AND TS = (Nigeria OR Nigerian).”

The inclusion criteria for the articles were as follows: 1) articles that focused on empirical or conceptual work on public policy-making, governance reforms, institutional change, or institutional performance in Nigeria’s Fourth Republic, 2) publications that explicitly discusses institutional drivers (e.g., political institutions, bureaucratic structures, legal frameworks, party systems, civil society, international actors) and/or governance outcomes (accountability, transparency, participation, effectiveness, rule of law), 3) publications within 1999 to 2025 to ensure the relevance of the findings, and 4) articles published in peer-reviewed journals or from reputable sources.

All records obtained were exported from both Web of Science and Scopus and then gathered into a reference management software for arranging and removal of duplicates. The initial database search in Scopus and Web of Science yielded a substantial output of 3650 records. After the duplicated were screened, we had an output of 2658 records. A meticulous abstract and title screening process, resulting in 122 articles advancing to the full-text evaluation stage. Then, the full-text screening was done to check the eligibility of the studies according to the predefined inclusion and exclusion criteria. This procedure made sure that only the studies with direct relevance to the research objectives were considered for final analysis. The selection process of studies was recorded by means of a PRISMA flow diagram as shown in Figure 1.

A narrative and thematic synthesis approach was utilized to integrate the outcomes. The studies were classified based on the themes that reappeared. This made it possible to find the main patterns, the shortcomings in the literature, and the places where the studies reviewed came together and where they differed. The synthesis was mainly concerned with following over time the institutional drivers for policy-making, policy reforms, and governance processes, which was the main aim of the study.

Figure 1. PRISMA flow chart.

The study used the Mixed Methods Appraisal Tool (MMAT) develoved by [18] to appraise the methodological rigor of the included papers. The methodological appraisal was carried out on all the studies included in the review and merged into the methods of this review was done with the intention of integrating the qualitative and quantitative methods. The 2018 MMAT was chosen since the included papers comprise qualitative, quantitative, and mixed-methods designs, and the tool permits a uniform appraisal across these different methodological traditions.

Among the reform focus identified, governance and public administration reforms are the ones that have received most attention, which shows that they are still consider as important the institutional bases of democratic governance that have existed since the beginning of Nigeria’s fourth republic as reported in the included studies. Table 1 simplifies the relationship between reform focus, sectoral focus and the key institutional dimensions.

Table 1. Reform focus and sectoral focus of governance reforms in Nigeria’s fourth republic (1999-2025).

The studies reviewed suggest that governance and institutional reforms in Nigeria’s Fourth Republic have produced mixed results and mainly incremental gains. The reforms across various policy areas have been rather conservative, and they are still very much part of the existing governance structures even though some adjustments may be noticed. Changes in formal rules, laws, and organizational arrangements are usually reported but these changes have not consistently resulted in changes in institutional behaviour or policy practice of a considerable magnitude ([3]; [6]).

All the studies point to a common finding which is the dominance of reforms that are either symbolic or procedural. In numerous situations, the creation of new institutions, strategies, or regulatory frameworks was not supported by any increase in enforcement capacity or compliance. This is particularly true for the reforms in accountability and anti-corruption where the institutional expansion on paper coincides with the existing governance problems ([11]; [16]). Consequently, the effects of the reforms are usually described as having low potency and being of a temporary nature.

Furthermore, some studies reported cases of reform stagnation and even reversal, particularly in the cases where reforms face political resistance or threaten the interests of the powerful ([4]; [11]; [27]). New government leaderships often change the reform momentum, resulting in inconsistent implementation and diminished institutional continuity. In such situations, power relations and political priorities are the main factors influencing the outcomes of the reform rather than the technical design.

Nonetheless, there are some studies that indicate small positive outcomes especially in the area where the reforms are backed by strong legal support, administrative capacity, and institutional stability. The accomplishments are for instance in the fields of procedural accountability, financial management systems, and coordination mechanisms ([28]; [37]). Yet even in these situations, improvements remain localized and fragile, lacking the systemic depth required for long-term institutional change.

Conclusively, the evidence from the included studies indicates that the reform results in Nigeria’s Fourth Republic are most appropriately characterized as gradual, irregular, and based on conditions, mirroring the relationship between concrete reform measures and the existing institutional limitations.

The papers reviewed uniformly point to institutional design and governance arrangements as decisive factors in the policy-making process during Nigeria’s Fourth Republic. The authority over policy, the methods of decision-making, and the routes of implementation are determined by the constitution, laws, and the formal structure of the organizations involved, and this is true for all sectors ([3]; [11]; [16]; [37]). More specifically, the federal system and the distribution of powers according to the constitution have a major impact on the policy-making and execution processes at the federal, state, and local government levels ([6]; [11]; [16]; [19]).

One of the main institutional drivers discussed in the reviewed studies is the bureaucratic capacity, which encompasses administrative capabilities, the stability of the organization, and the professional standards in public institutions. Result shows that policy performance differences are strongly tied to institutional capacity differences; in other words, the better the resources and professional expertise of the agency, the stronger the policy implementation outcomes they will have ([3]; [4]; [11]). On the other hand, inadequate administrative systems are frequently associated with policy delays, gaps in implementation, and failures in coordination ([24]; [33]).

Finally, the political-institutional relations, particularly executive dominance in the policy-making process, are pointed out as another significant factor ([3]; [6]; [19]; [37]). The executive branch’s control over decision-making shapes the priority of policies and limits the power of the legislature to oversee and the institutions to be accountable. This interplay impacts both the making and the executing of policies, often restricting the freedom of the regulatory and monitoring bodies in their actions.

One of the very important aspects that the results of this review reveals is the power of governance capacity in policy matters. The findings reveal that capacity building for governance has enabled pockets of effectiveness to emerge in certain policy sectors, especially in public financial management and at the same time, left the wider administrative state unable to function adequately. For instance, the reforms like the Treasury Single Account (TSA) and Integrated Personnel and Payroll Information System (IPPIS) have shown that the state can drastically cut down on leakages, manage cash better, and restore budget credibility when there is a combination of central political power, clear institutional roles, and ICT tools ([19]; [28]; [37]). These results indicate that the Nigerian state is not totally weak; on the contrary, it is capable to a certain extent, particularly where reforms are in line with elite interests (e.g. fiscal consolidation, central control anti-leakage measures) and attract international legitimacy. Such revelations further reinforce the opinion that the issue of Nigeria’s policy failures is not so much about the design of the policies but rather the limitations of the state capacity ([9]; [38]).

The review results further highlight the lasting inadequacies in the accountability of institutions, particularly in the areas of legislative control, judicial independence, and regulatory enforcement, which gives room for executive dominance. In their research, [27] argue that even though the 1999 Constitution stipulates that the legislative and executive branches are equal and that there is legislative monitoring, the relationships between the legislature and the executive have been more conflictual than collaborative, marked by power struggles, threats of impeachment, and coalitions based on limited political interests rather than governance through policies. This situation is a hindrance to the legislature in terms of its role as an effective counterbalance, thereby resulting in policy instability, the slow process of passing laws and poor delivery of services ([29]).

This incident is more common with the anti-corruption agencies like the EFCC and ICPC. While endowed with formal autonomy, their effectiveness has fluctuated with changes in political leadership, reinforcing the finding that formal institutional design alone is insufficient without political insulation and enforcement credibility ([32]). Thus, the review strengthens the view that the institutional framework for accountability in Nigeria is still not fully developed, thereby affecting the credibility of the policy and the trust of the public.

Among the various outcomes noticed in the studies that were reviewed, the impact of elite capture and informal institutions on the reform paths taken was the most striking one ([3]; [33]). The situation of corruption has not changed much, remaining to be the same as before in the forms of political financing, procurement systems, and intergovernmental transfers, while anti-corruption policies and institutions have been proliferating all the time ([15]). This is consistent with the findings of the review which reveal that the elites usually have the say when it comes to the reforms and they do so by making the implementation only partially compliant, watering down the policy or plain resistance. This, in turn, backs up the institutionalist claims that distributional coalitions will not give up unless the reforms do not breach their interests ([12]).

The evidence presented here goes against the standard view that decentralization directly leads to improved governance ([2]; [17]). However, it is still argued that the results of decentralization depend on the sequence of the institutional changes, the building of capacities, and the links of accountability, which have been poor or inconsistent in Nigeria. This agrees with [1] which enforces the important of institutional capacity, fiscal autonomy and institutional accountability as contextual factors for successful decentralization.

According to [6], the establishment of new local government areas resulted in the higher development rankings of some areas, thus indicating that decentralization can improve local access to state resources and encourage regional development if the conditions are right. At the same time, continuous bureaucratic hurdles, shortage of skilled personnel, and corruption in the civil service restricted the wider application of these territorial changes in service delivery ([6]; [13]; [22]).