The law requires that all foreigners residing within Kenya for a period exceeding 90 days be registered.

Requirements

Online application done on https://fns.immigration.go.ke and printout form 50 and payment acknowledgment
Copy of valid passport bio data page
Proof of residence (permit, permanent residency, dependent/student pass)
Two colored current passport photographs (white background)
Copy of previous alien card (renewal cases)
A charge of ksh 1000 per year (or part thereof)

Registration process

Booking of an appointment for submission of application
Receiving, verifying and approving application documents presented by foreign national on the appointment day.
Capture of biometrics attributes (facial features & Finger prints)
Issue of waiting slip to applicant pending production of foreigner certificate
The applicant is notified to collect their card once ready via the account used to submit the application
The production of the card takes several weeks as it is done centrally by the National Registration Bureau who query the captured biometrics against their databases of Citizens and refugees. They keep a register for new applicants.
The following persons are exempted from Foreign National Registration.

Serving member of the armed forces
An embassy/consular staff posted in Kenya as well as their spouse and children
A person exempted from the provisions of the Act under section 34(3) of the Act
A refugee registered under the refugee Act 2006
A person who resides in Kenya for a continuous period not exceeding three months and is in possession of visitors pass or special pass.