Nairobi and Kiambu account for the largest population of the 19,611,423 registered voters eligible to take part in the August 8 general elections.
IEBC data released on Tuesday showed that Nairobi leads with a total of 2,250,853 voters followed by Kiambu which has 1,180,920 eligible voters.
The two counties are home to 17.4 per cent of the voters in the country.
Nakuru came third having registered 949,618 voters followed by Kakamega's 743, 736 and Meru's 702, 480.
Machakos emerged sixth with 620,254 voters followed by Murang'a which has 587,126 voters while Mombasa is position eight with 580,223.
The Coastal county is followed by Bungoma which has listed 559,850 voters whereas Kisii closes top 10 counties with 546,580 voters.
Kisumu is in position 11 with 539,210 voters followed by Kilifi (508,068), Homa Bay (476, 875), Kitui (475,512) and Siaya (457,953).
Nyeri county is position 16 with 456,949 voters followed by Uasin Gishu, Makueni, Kajiado and Migori with 450,055; 423,310; 411,193 and 388,633 respectively.
Kericho came at position 21 with 375,668 registered voters followed by Busia (351,048), Kirinyaga (349,836), Nandi (346,007) and Narok (341,730).
Trans Nzoia, the electoral agency data suggests, is position 26 with 339,622 voters followed by Nyandarua with 335,634 registered voters.
Isaac Rutto's Bomet county took position 28 with 322,012 voters followed by Embu with 309,466. Kwale is at position 30 with 281,041 voters.
While Nyamira has a total of 278,583 voters, Vihiga follows closely with 272,409 while Laikipia has 246,487 registered voters.
Baringo, in the verified register, has 232,558 voters while Jubilee's perceived Tharaka Nithi stronghold is at position 35 with 213,154 voters.
Turkana is among the counties with less than 200,000 voters with a total of 191,435 registered voters.
It is followed closely by Elgeyo Marakwet with 180,664, West Pokot (180,232), Mandera (175,642) and Garissa at position 40 with 163,350 listed voters.
Wajir county has 162,902 voters compared to Taita Taveta which has 155,716 followed by Marsabit with 141,708 voters.
Tana River is at position 44 with 118,327 voters hence closes the list of counties with more than 100,000 voters.
Samburu, on the other hand, has 82,787 registered voters, Isiolo (75,338) with Lamu trailing all the 47 regional units with only 69,776 registered voters.
In the latest update released by the electoral agency on Tuesday, at least 4,393 voters in the diaspora are eligible for the polls whereas 5,528 will vote in prison.
The number represents the number of voters whose details were verified and found to be up to date.
Some 88,602 voters were expunged from the register after a forensic audit done by KPMG clarified that they were dead.