Nigeria is not a party to the Apostille Convention which specifies the modalities through which a document issued in one of the signatory countries (to the Apostille Convention) can be certified for legal purposes in all the other signatory states.

Hence attestation of Nigerian issued documents usually follow a particular process, depending on the type of document and the country such document is sought to be used. Regardless of the process or type of document however, the attestation process is called legalization.

We have highlighted below what a typical document legalization exercise will entail for use abroad:
Notarization: notarization is the official fraud-deterrent process that assures the parties of a transaction that a document is authentic, and can be trusted. It is a three-part process, performed by a Notary Public, that includes vetting, certifying and record-keeping of the document. Some embassies require that the document sought to legalized be first notarized by a notary public in Nigeria. It is pertinent to state that certain embassies have a list of certified notaries public that must be used.
Translation: some countries will also require that the relevant document be translated to the official language of the country in which the document is sought to be used before approaching the embassy for legalization. It is also noteworthy that certain embassies have their list of certified translators that must be used as well.
Authentication by Ministry of Foreign Affairs (MOFA): the final step of certifying the authenticity of Nigerian issued document before approaching the embassy of the foreign country is certification by MOFA. MOFA will upon payment of the prescribed fees and verification of the document, engrave its seal on the document, thereby certifying the authenticity of the relevant document.
Authentication by Ministry of Education (MoE): In addition to authentication by MOFA, education certificates are required to be authenticated by the MoE. The MoE requirement for education document is required to be done before the MOFA authentication above. The process at the MoE is similar to that at MOFA.
Legalization at the embassy: this is usually the final stage in the legalization cycle and it entails the embassy ensuring all the previous attestation the document has gone through are genuine. This is done by trained inhouse personnel of the embassy or by consulting external investigators. Once the embassy is satisfied of the authenticity of the document and the prescribed fees are paid, the embassy will legalize the document, thereby certifying it appropriate for use abroad.
Conclusion
As straight forward as attesting/legalizing a document may seem, it is always best to employ the services of trained practitioners who are familiar with the process in other to avoid potential pitfalls. 
Important notes:
Different countries have different requirements for legalization. Some countries may require some or all of the steps highlighted above. Others may even have additional requirements;
Legalization fees at the embassy may be subject to foreign exchange rates; and
Certain documents have a timeline within which they must be legalized once issued.
For questions and clarifications, please do not hesitate to contact Busayo Adedeji at:
Busayo.adedeji@newedege-consultants.com and +2348034476429.