BEST WAY DOWNTOWN:
The airport is located 11 miles (18 km) southeast of the center of Nairobi.
Taxis in Nairobi are a challenge, as they are in many other cities. The best bet, recommended by Kenya Airways, is the Mercedes taxi, awaiting the weary (or not) traveler in front of the airport's terminal. A Mercedes taxi will take you to the central city hotels for a fixed fare, currently about 900 Kenyan schilling ($12). The taxis are government-sponsoredlook for the Kenya seal on the side.
Regular taxis are also available, and you will also find a number of drivers eager to give you a ride to the center. If you don't negotiate the fare, you will end up paying the same, or more, as you would have with the Mercedes taxis. Regular taxi fare to central Nairobi will be around 400-500 Kenyan schilling ($5-6). If you are going to pay much more, you might as well go with the nice taxis. Journey time is from 20-30 minutes.
Buses to central Nairobi are available from in front of the terminal. Fare is 50 to 80 Kenyan schilling (under one dollar). There's almost no room for luggage, and it will take 30 to 40 minutes for the trip.
Avis, Europcar, Hertz, along with a few local companies, have offices in Nairobi.
World Airport Information Main Page
Adapted from How to Get Out of the Airport