Thairu featured for Kawangware United in the premier league up to 2002 but left to join the newly formed World Hope in 2003.
He was part of the squad that promoted the side to the Kenyan Premier League in the 2004/5 season.
The goals included a hattrick in the 2011 season-ender that led to a 4-2 win over Karuturi Sports at Hope centre.
[2][3] He remained active in football after 2013 by featuring for lower-tier sides in tournaments as player and coach[4] before making a return to the top flight league once again when he joined Nakumatt FC in 2019.
[5] Thairu is the elder sibling of Anthony Kimani, the current Nairobi City Stars captain.