The workers were arrested after an impromptu visit by Sonko.
The county workers were charged with being in possession of Sh7 million.
The move follows last week's sting operation at City Hall where Sh7 million in cash was found with City Hall workers.
Sonko personally led the raid at the County Cash Offices following a tipoff from an anonymous source and found the stash.
The governor was accompanied by his deputy, Polycarp Igathe during the sting operation that seemed to have caught many at the offices offguard.
After the raid, Sonko ordered that the cash office be immediately installed with CCTV cameras at City Hall and instructed that monitoring of the same be done by his office, the Criminal Investigations Department (CID) and the National Intelligence Service (NIS).
The governor has already written to Web Tribe Ltd, the owners of JamboPay and Jijipay platform which has been contracted to operate the electronic payment platform for cash collections, demanding to know how much revenue they have collected within the past two weeks.
Earlier this week, issued a new order directing all cash flow within City Hall to be fully automated in order to seal all loopholes that lead to theft.
“Nobody will be allowed to pay cash to acquire any service. I also intend to increase annual revenue from Sh15.5 billion to 30 billion. My government will also ensure proper streamlined decentralisation of services to ensure this is achieved,” Sonko said.