Nigeria’s central bank said non-registered customers would lose all the benefits attached to online banking until they register.
The exercise is aimed at reducing fraud in the country’s banking sector.
Huge sums are allegedly stolen from Nigerian banks as a result of either forgeries or illegal withdrawals.
People were asked to enrol at their local banks to have their fingerprints taken, along with a photograph of their face.
The bank then issues customers with a unique Bank Verification Number, which is used in combination with the biometric information to confirm their identity whenever a transaction is made.
Central bank spokesman Ibrahim Mu’azu told the BBC Hausa service that the exercise has been on going for more than two years but less than half of the 52 million account holders have so far registered.
As the banks are not open on Saturday and Sunday, Friday is effectively the last day people can get the number.
There was a last-minute rush in June as people tried to register, before the deadline was extended to 31 October.
However, the situation appears to be calmer on Friday.
The bank has also set up centres in Europe and America to allow Nigerians in the diaspora to register.