The court also ordered that the petitioners be paid Sh2 million suit cost.
Justice Sila Munyao on Thursday declared null and void the licences allowing establishment of the Sh15 billionwind power plant.
Munyao said, however, his decision does not mean the court is against the project or mark the end of the key energy investment, which is a vital government venture and part of Vision 2030 projects.
Munyao ruled there were irregularities in licensing the plant in Nyandarua county.
The court ruled the environmental impact assessment report giving the project the green light was illegally varied by the National Environment Management Authority.
He said regulations have to be followed without shortcuts to avoid adverse environmental impacts.
“Our predecessors have unjustifiably destroyed the environment and we are now trying to mitigate that to avoid adverse impacts,” the judge said.
He ordered Kinangop Wind Park managers to conduct fresh environmental impact assessment if it wants to proceed with the project.
Munyao said the project is likely to violate the petitioners’ rights to a clean and healthy environment and affect their livelihoods.
The court established a substantial change has occurred since the project was launched in 2005.
These include increase of project area from two to 16 square kilometres, and from initial target of 30 to 61 megawatts of electricity generation.
Some residents sued the Kinangop Wind Park, Nema, the National Land Commission and the company that conducted the EIA.
They said the project has hurt their environment.
The Kinangop Wind Park, which withdrew from the project in February, had reportedly invested Sh6.7 billion.