[2] Ndiku made his international debut at the 2007 World Youth Championships in Athletics, coming fourth in the 2000 metres steeplechase event.

Working with Teren, Ndiku's technique over the barriers greatly improved and one year later he won the gold medal at the 2008 World Junior Championships in Athletics, beating Uganda's Benjamin Kiplagat who had built up a sizeable lead in the early stages.

[8] He won the steeplechase title at the 2009 African Junior Athletics Championships, despite having lost one of his running spikes in the first half of the race.

"[14] Success also came in flat races that year as he won both the 1500 m and 5000 m Japan Corporate Championship titles, including a personal best of 3:39.27 minutes.

[15] He competed on the 2011 IAAF Diamond League circuit and set a personal best of 8:07.75 minutes for sixth place at the Herculis meeting – a time which ranked him the ninth fastest in the world that year.

In the steeplechase he opened with a run of 8:10.72 minutes (his fastest time since 2011) which brought him third place at the IAAF World Challenge Beijing behind Paul Kipsiele Koech and Jairus Birech.

[19] He was chosen for the 2014 Commonwealth Games and was the least favoured entrant of the Kenyan team behind world-leader Birech and reigning world and Olympic champion Ezekiel Kemboi.

However, Ndiku completed an upset by keeping with the pair before pulling ahead in the final lap to win the gold medal in a Games record time of 8:10.44 minutes.