Ambassador Samuel Wamathai has been sworn in as the new Nyeri governor.
Mr Wamathai, the former deputy county boss, on Monday took the oath of office at the county headquarters with a pledge to fight corruption.
The swearing-in, presided over by Resident Judge Jarius Ngaah, is likely to heighten anxiety on the composition of a new Cabinet.
Speaking moments after the ceremony, Mr Wamathai said he would effectively execute his duties without fear.
"I demand total honesty and integrity from everyone working in the county," he said. "I will not tolerate acts of corruption and dishonesty."
County Secretary Alice Wachira received the new county first lady Leah Njoki, who has not been in the public limelight.
Most Nyeri MPs, however, snubbed the event with only Tetu MP Ndung'u Gethenji present.
The lawmaker said he was representing the rest at the event attended by at least 12 members of the county assembly, led by their Speaker David Mugo.
Mr Mugo said the assembly would support the new governor.
He said the MCAs differences with Mr Gachagua were not personal and the assembly was only doing its job.
Chairman of the Council of Governor Peter Munya was the only county boss present.
Hundreds of Nyeri residents gathered at the Nyeri County headquarters for the swearing-in. The seat fell vacant following the death of Nderitu Gachagua in a London hospital on Friday.
Relatives of the late governor were represented by his younger brother Rigathi Gachagua. The family promised to fully support the incoming governor noting that he had been a pillar of strength for the family.
“The incoming governor has been a blessing to the county because, were it not for him, when the governor had been indisposed the county would have ground to a halt,” said Mr Rigathi, the family spokesman.
“He deserves the support.”