Harambee Stars fans trooped to Kasarani Stadium from as early as 6am Sunday ahead of the 4pm encounter with Ethiopia.
Kenya needs a goal to top Afcon 2019 Group F qualifiers which also has Ghana and Sierra Leone.
Long queues were witnessed outside the stadium. The government announced a free entry to the 60,000 capacity arena.
Some fans travelled from as far as Mombasa. Governor Hassan Joho flagged off 10 buses which arrived in Nairobi this morning.
His Nairobi counterpart Mike Sonko released 150 buses which are expected to ferry more people to the match.
The team coordinating the Kasasrani transport in Nairobi set up 12 picking points.
The early response by Kenyans was a subject of a KOT conversation as some users wondered why people woke up that early.
Pyew Waw wrote: “The game is at 4pm but guys are already getting into the stadium this early. There’s a thin line between patriotism and idleness.”
“Kasarani Stadium is fully packed! The Vuvuzela atmosphere is all I hear! This is the patriotism we need!” a user tweeted.
Several leaders wished the Kenyan team well ahead of the match.
Key to note was Ford Kenya leader Moses Wetang’ula, ODM’s Raila Odinga, Narok Senator Ledama Ole Kina among many others.
It is hoped that Harambee Stars will end their 15-year wait to reach the African Cup of Nations finals.