The three colluded to steal Sh8.8 million in approval fees from the county.
The Milimani law courts found Esther Nyambura Thongori, George Githurai Karume and Bonny Stephen Otieno Oduor guilty of conspiring to commit an economic crime by receiving and retaining the amount for building plans in the city.
Nyambura is a clerical officer, Githuri a building inspector while Otieno is a private developer.
The court also found them guilty of conspiracy to defraud, obtaining money by false pretense and making false documents.
The court fined each of the three Sh700,000 or jail term of 12 months, a mandatory amount of Sh280,000 or jail term of three years and a another fine of Sh 50,000 each or jail term of six months.
This means that they have to part with Sh1 million each to secure their freedom.
They were taken to the Industrial Area Prison where they will be locked until they clear the stated fine or serve jail.
Following the court decision, Governor Mike Sonko has asked the public and all county officials to strictly follow the law in executing operations.
Sonko has warned against payment of kickbacks or suspect fees for any services at City Hall.
“This should serve as a good example to those who want to bend our laws and do things through the backdoor,” Sonko said.
He said that all charges for county services are captured in the Finance Bill, 2019 which he signed into law on Tuesday.
Last month, the Governor suspended 16 county officials from the planning department, including two executives, to pave way for investigations into circumstances under which a wall collapsed at Precious Talent Academy killing eight pupils.
Sonko has also initiated a thorough audit of the planning department to try and unmask past irregularities in the sector.