What you need to know:
Mr Haji said he had sufficient evidence to prosecute Mr Sonko and other county officials for "unlawful acquisition of public property, money laundering and other economic crimes."
Nairobi Governor Mike Sonko was arrested Friday shortly after the chief prosecutor ordered he be detained to face charges of economic crimes.
Mr Sonko is the latest in a string of top officials, including Finance Minister Henry Rotch, to be hauled in on corruption charges as Kenya battles to clamp down on rampant graft.
"The Governor of Nairobi Mike Sonko has been arrested by our officers in Voi. He is being escorted to Nairobi to face charges in court," Yassin Amaro, spokesman for the Ethics and Anti-Corruption Commission (EACC) said Friday.
The flashy governor and other country officials are accused by public prosecutor Noordin Haji of having benefitted from irregular procurement and payments of Sh357 million.
Mr Haji said he had sufficient evidence to prosecute Sonko and other county officials for "unlawful acquisition of public property, money laundering and other economic crimes."
It was seen as a maverick move when, in 2017, the ruling party chose populist Mike Sonko as its candidate for Nairobi's gubernatorial poll, a controversial politician who has spent time in jail and has had to deny allegations of illegal activities, including drug trafficking.
Mr Haji said his investigation into Sonko and his officials had been challenging "because of the repeated attempts by the accused to obstruct the course of the investigations by deploying intimidation tactics in addition to using goons to threaten law enforcement officials carrying out their constitutional mandates."
Since his election, Sonko has chosen to operate from his rural home in Machakos, 60 kilometres southeast of Nairobi.
He is beloved by poor Kenyans for running his personally branded fire trucks and ambulances to assist people living in the slums.
He is also known for wearing expensive gold jewelry and bright golden shoes and recently drew criticism for displaying his opulent dining room on social media.
Kenya has for decades battled the scourge of corruption, and President Uhuru Kenyatta -- like many presidents before him -- has vowed to combat graft.
Dozens of top executives and government officials have been charged since Kenyatta's 2017 re-election, including sitting Finance Minister Henry Rotich who was in July charged over an alleged multi-million dollar corruption scandal.