The Judge has ruled
Gakuo, who previously served as Nairobi Town Clerk, was found guilty alongside former Local Government PS Sammy Kirui.
The two have also been handed a Sh1 million fine.
Also found guilty was former Secretary to defunct Nairobi City Council Mary Ngethe and then tender committee chair Alexander Musee - they were also jailed for three years and fined Sh52m and Sh32m respectively.
The Sh283 million scandal becomes the biggest case where powerful government officials have been sentenced to jail over corruption.
Gakuo's reign as Town Clerk witnessed relative success in cleaning of the Nairobi River and getting rid of the parking children in CBD.
His term was, however, was cut short after President Mwai Kibaki dismissed him over the Mavoko land cemetery scandal.
Nairobi Governor Mike Sonko had earlier indicated Gakuo as one of the potential nominees for position of Deputy Governor.
In February, Sonko picked the former Town Clerk to replace Polycarp Igathe as Chairman of the Nairobi Regeneration Committee.