Simon Mbilu was born the eldest of six siblings in 1942 in Mombasa, an island town of the Indian ocean coast of Kenya. He is a member of the Akamba ethnic group. His father Mr. Kithuku, then working for the Kenya Railway, moved back to his ancestral village of Mulango in Kitui when Mbilu was two years old.
Simon Mbilu attended Kitui Primary School and then Kitui High School. He was later accepted to Shimo La Tewa High School where he completed form five and six at the top of his class. He applied and was accepted to Makerere University where he intended to study Law.
At this time, Kenya was a new country and had just attained independence. The Kenya Armed Forces was on a quest to recruit the countries top talent, he was drafted into the Kenya Navy.
He was also able to attain further training and studies at the Britannia Royal Naval College under the sponsorship of the Kenyan navy.
In 1978, The first Kenya Navy Commander Lieutenant Colonel Kimaro was involved in a tragic road accident where he died and Mbilu, a brigadier at the time took over the command of the Navy as Major E S Mbilu . He served for ten years until his retirement in 1988 where he was replaced by Brigadier JRE Kibwana who was promoted to Major General and appointed the Navy Commander.
After his navy career, he also served briefly as chairman of the Kenya Airports Authority.
Simon Mbilu has six wonderful children from his first wife Avia Mbilu: Son Peter ; Daughters Marie, Betty, Nancy, Julie and Esther. Grand children: seven grandsons and five granddaughters.