Post developed from the original by Olabode Peculiar
1. Get your NIN (be sure the information on your NIN profile matches the one on your passport). If. You don't have a NIN or the information on your NIN is incorrect (name and date of birth) first go to one of their centres around you to update it or get one. For list of NIN centres close to you check https://nimc.gov.ng/uk-enrolment-centres/
2. After your NIN is sorted, apply online for renewal of your passport by completing the application form. It requires you to have an account already, you may click signin to reveal the signup details. https://passportintl.immigration.gov.ng/
You will find the fees for the passport on immigration page.
You should printout the application acknowledgement slip
3. After completing the application form book your biometrics appointment. To book your biometrics appointment go to https://appointments.immigration.gov.ng/ make sure you printout your confirmation of appointment slip.
4. Proceed to post office and buy:
(a) A £20 postal order in favour of Nigeria High Commission (most post office only accept cash payment for this so please go with cash)
(b) A self addressed return envelope with stamp if you are outside London and don't want to return their to pick your passport up by yourself.
5. On your appointment date, attend your biometrics appointment with the following documents:
Copy of the acknowledgement slip
Copy of biometrics appointment booking
£20 postal order
The self addressed envelope with stamp (for the return of your passport)
Original of Expiring/expired passport
Address of Nigeria High Commission in London: 9 Northumberland Ave, London WC2N 5BX
NB: things change with time, always refer to Immigration page online for further reference..